Tìm a, b sao cho $\frac{\text{4x}-\text{7}}{{\text{x}}^{\text{2}}-\text{3x}+\text{2}}=\frac{\text{a}}{\text{x}-\text{1}}+\frac{\text{b}}{\text{x}-\text{2}}$ ?

A. a = 3, b = 1.

B. a = -3, b = 1.

C. a = 3, b = -1.

D. a = -3, b = -1.

Tìm a, b sao cho $\frac{\text{1}}{\text{(x}+\text{1)(x}-\text{1)}}=\frac{\text{a}}{\text{x}+\text{1}}+\frac{\text{b}}{\text{x}-\text{1}}$

A. $a = \frac{-1}{2}; b = \frac{-1}{2}$

B. $a = \frac{1}{2}; b = \frac{1}{2}$

C. $a = \frac{1}{2}; b = \frac{-1}{2}$

D. $a = \frac{-1}{2}; b = \frac{1}{2}$

Cho 2a - b = 7; $a \ne \frac{-7}{3}$ ; $b \ne \frac{7}{2}$ . Tính giá trị của biểu thức

A = $\frac{\text{5a}-\text{b}}{\text{3a}+\text{7}}+\frac{\text{3b}-\text{2a}}{\text{2b}-\text{7}}$ .

A. 3

B. 4

C. 1

D. 2

Cho 3y - x = 6. Tính giá trị của biểu thức P = $\frac{\text{x}}{\text{y}-\text{2}}+\frac{\text{2x}-\text{3y}}{\text{x}-\text{6}}$ .

A. 3

B. 4

C. 1

D. 2

Kết luận nào sau đây là đúng khi nói về giá trị của biểu thức

M = $\frac{\text{10}}{\text{(x}+\text{2)(3}-\text{x)}}-\frac{\text{12}}{\text{(3}-\text{x)(3}+\text{x)}}-\frac{\text{1}}{\text{(x}+\text{3)(x}+\text{2)}}$  với x = -0,25?

A. M = 16.

B. M > 1.

C. M < 0.

D. 0 < M < 1.

Kết luận nào sau đây là đúng khi nói về giá trị của các biểu thức

B = $\frac{\text{x}}{{\text{x}}^{\text{3}}+\text{1}}+\frac{\text{1}-\text{x}}{{\text{x}}^{\text{2}}-\text{x}+\text{1}}+\frac{\text{1}}{\text{x}+\text{1}}$  với x = -2?

A. B > 0.

B. B < -1.

C. B < 0.

D. B > 1.

Giá trị của biểu thức P = $\frac{{\text{6x}}^{\text{2}}+\text{8x}+\text{7}}{{\text{x}}^{\text{3}}-\text{1}}+\frac{\text{x}}{{\text{x}}^{\text{2}}+\text{x}+\text{1}}-\frac{\text{6}}{\text{x}-\text{1}}$  với x = $\frac{1}{2}$ là?

A. -2

B. 2

C. $\frac{1}{2}$

D. $-\frac{1}{2}$

Giá trị của biểu thức C = $\frac{\text{1}}{\text{x}-\text{18}}-\frac{\text{1}}{\text{x}+\text{2}}$  với x = 2018 là?

A. $\frac{\text{1}}{\text{2020}}$

B. $\frac{\text{1}}{\text{202000}}$

C. $\frac{\text{1}}{\text{20200}}$

D. $\frac{\text{1}}{\text{200200}}$

Cho D = $\frac{{\text{5x}}^{\text{2}}}{\text{5x}-\text{6}}+\frac{{\text{x}}^{\text{2}}-\text{1}}{\text{6}-\text{5x}}-\frac{\text{7}+\text{x}-{\text{x}}^{\text{2}}}{\text{5x}-\text{6}}$ . Sau khi thu gọn hoàn toàn thì D có tử thức là?

A. x

B. x + 1

C. $\frac{\text{x}}{\text{x}-\text{1}}$

D. $\frac{\text{x}}{\text{x+1}}$

Cho B = $\frac{\text{1}}{{\text{x}}^{\text{2}}-\text{x}+\text{1}}+\text{1}-\frac{{\text{x}}^{\text{2}}+\text{2}}{{\text{x}}^{\text{3}}+\text{1}}$ . Sau khi thu gọn hoàn toàn thì B có tử thức là:

A. x

B. x + 1

C. $\frac{\text{x}}{\text{x}-\text{1}}$

D. $\frac{\text{x}}{\text{x+1}}$

Thu gọn biểu thức M = $\frac{{\text{4x}}^{\text{2}}-\text{3x}+\text{5}}{{\text{x}}^{\text{3}}-\text{1}}-\frac{\text{1}-\text{2x}}{{\text{x}}^{\text{2}}+\text{x}+\text{1}}-\frac{\text{6}}{\text{x}-\text{1}}$  ta được?

A. $\frac{-\text{12x}}{{\text{x}}^{\text{3}}-\text{1}}$

B. $\frac{-\text{12}}{{\text{x}}^{\text{3}}-\text{1}}$

C. $\frac{-\text{x}}{{\text{x}}^{\text{3}}-\text{1}}$

D. $\frac{3}{{\text{x}}^{\text{3}}-\text{1}}$

Thu gọn biểu thức A = $\frac{\text{3x}+\text{21}}{{\text{x}}^{\text{2}}-\text{9}}+\frac{\text{2}}{\text{x}+\text{3}}-\frac{\text{3}}{\text{x}-\text{3}}$  ta được?

A. $\frac{-\text{2}}{\text{x}-\text{3}}$

B. $\frac{\text{2x}}{\text{(x}-\text{3)(x}+\text{3)}}$

C. $\frac{\text{2}}{\text{x}+\text{3}}$

D. $\frac{\text{2}}{\text{x}-\text{3}}$

Thực hiện phép tính $\frac{\text{a}}{\text{a}+\text{1}}-\frac{\text{a}}{\text{a}-\text{1}}-\frac{{\text{2a}}^{\text{2}}}{\text{1}-{\text{a}}^{\text{2}}}$  ta được kết quả gọn nhất là?

A. $\frac{\text{2a}}{\text{a}-\text{1}}$

B. $\frac{{\text{2a}}^{\text{2}}+\text{2a}}{\text{(a}-\text{1)(a}+\text{1)}}$

C. $\frac{\text{2a}}{\text{a}+\text{1}}$

D. $-\frac{{\text{2a}}^{\text{2}}}{\text{(a}-\text{1)(a}+\text{1)}}$

Chọn câu sai?

A. $\frac{\text{11x}+\text{13}}{\text{3x}-\text{3}}+\frac{\text{15x}+\text{17}}{\text{4}-\text{4x}}=\frac{-\text{1}}{\text{12}}$

B. $\frac{\text{11x}+\text{13}}{\text{3x}-\text{3}}+\frac{\text{15x}+\text{17}}{\text{4}-\text{4x}}=\frac{-\text{x}-\text{1}}{\text{12(x}-\text{1)}}$

C. $\frac{\text{xy}}{{\text{x}}^{\text{2}}-{\text{y}}^{\text{2}}}-\frac{{\text{x}}^{\text{2}}}{{\text{y}}^{\text{2}}-{\text{x}}^{\text{2}}}=\frac{\text{x}}{\text{x}-\text{y}}$

D. $\frac{\text{xy}}{{\text{x}}^{\text{2}}-{\text{y}}^{\text{2}}}-\frac{{\text{x}}^{\text{2}}}{{\text{y}}^{\text{2}}-{\text{x}}^{\text{2}}}=\frac{-\text{x}}{\text{y}-\text{x}}$

Chọn câu đúng?

A. $\frac{\text{3x}-\text{4}}{{\text{4x}}^{\text{2}}{\text{y}}^{\text{5}}}+\frac{\text{9x}+\text{4}}{{\text{4x}}^{\text{2}}{\text{y}}^{\text{5}}}=\frac{\text{3}}{{\text{xy}}^{\text{4}}}$

B. $\frac{\text{2x}+\text{5}}{\text{3}}+\frac{\text{x}-\text{2}}{\text{3}}=\frac{\text{x}+\text{1}}{\text{3}}$

C. $\frac{\text{x}+\text{8}}{\text{x}-\text{1}}-\frac{\text{2x}-\text{1}}{\text{x}-\text{1}}-\frac{\text{6x}+\text{2}}{\text{x}-\text{1}}=\text{7}$

D. $\frac{\text{x}}{\text{x}-\text{y}}+\frac{\text{y}}{\text{x}+\text{y}}+\frac{{\text{2y}}^{\text{2}}}{{\text{x}}^{\text{2}}-{\text{y}}^{\text{2}}}=\frac{\text{x}+\text{y}}{\text{x}-\text{y}}$

Chọn câu đúng?

A. $\frac{\text{1}}{\text{x}+\text{2}}-\frac{\text{1}}{\text{(x}+\text{2)(4x}+\text{7)}}=\frac{\text{4x}}{\text{(x}+\text{2)(4x}+\text{7)}}$

B. $\frac{\text{2}-\text{21x}}{\text{18}}-\frac{\text{4}+\text{x}}{\text{12}}=\frac{\text{75x}-\text{16}}{\text{36}}$

C. $\frac{\text{1}}{\text{x}+\text{4}}-\frac{\text{1}}{\text{x}+\text{5}}=\frac{\text{1}}{\text{(x}+\text{4)(x}+\text{5)}}$

D. $\frac{\text{2}}{\text{x}-\text{5}}+\frac{\text{3x}}{{\text{x}}^{\text{2}}-\text{25}}=\frac{\text{4x}+\text{5}}{{\text{x}}^{\text{2}}-\text{25}}$

Điền vào chỗ trống: $\frac{\text{2x}-\text{6}}{\text{x}+\text{3}}-\mathrm{....}=\frac{\text{x}+\text{1}}{\text{2}}$ .

A. $\frac{-{\text{x}}^{\text{2}}+\text{15}}{\text{2(x}+\text{3)}}$

B. $\frac{{\text{x}}^{\text{2}}-\text{15}}{\text{2(x}+\text{3)}}$

C. $\frac{-{\text{x}}^{\text{2}}-\text{15}}{\text{2(x}+\text{3)}}$

D. Cả A, B, C đều sai

Kết quả gọn nhất của phép tính $\frac{\text{x}-\text{2}}{{\text{6x}}^{\text{2}}-\text{6x}}-\frac{\text{1}}{{\text{4x}}^{\text{2}}-\text{4}}$  là một phân thức có tử thức là?

A. $2x^2 + 5x - 4$

B. $\frac{{\text{2x}}^{\text{2}}-\text{5x}-\text{4}}{\text{12x(x}-\text{1)(x}+\text{1)}}$

C. $2x^2 - 4x - 4$

D. $2x^2 - 5x - 4$

Phép tính $\frac{\text{1}}{\text{x}+\text{1}}+\frac{\text{1}}{\text{1}-\text{x}}+\frac{{\text{2x}}^{\text{2}}}{{\text{x}}^{\text{2}}-\text{1}}$  có kết quả là?

A. $\frac{{\text{x}}^{\text{2}}+\text{2x}}{\text{(x}-\text{1)(x}+\text{1)}}$

B. 2

C. $\frac{{\text{2x}}^{\text{2}}+\text{2}}{\text{(x}-\text{1)(x}+\text{1)}}$

D. $\frac{{\text{2x}}^{\text{2}}}{{\text{x}}^{\text{2}}-\text{1}}$

Phép tính $\frac{\text{2}}{\text{x}+\text{3}}-\frac{\text{3}}{{\text{x}}^{\text{2}}-\text{9}}$  có kết quả là?

A. $\frac{\text{2x}-\text{9}}{{\text{x}}^{\text{2}}-\text{9}}$

B. $\frac{\text{2x}-\text{3}}{{\text{x}}^{\text{2}}-\text{9}}$

C. $\frac{\text{2x}-\text{9}}{\text{x}-\text{3}}$

D. $\frac{\text{x}-\text{6}}{{\text{x}}^{\text{2}}-\text{9}}$

Kết quả của tổng $\frac{\text{x}}{\text{xy}-{\text{y}}^{\text{2}}}+\frac{\text{2x}-\text{y}}{\text{xy}-{\text{x}}^{\text{2}}}$  là?

A. $\frac{-\text{x}+\text{y}}{\text{xy}}$

B. $\frac{\text{x}-\text{y}}{\text{x}}$

C. $\frac{\text{x}-\text{y}}{\text{y}}$

D. $\frac{\text{x}-\text{y}}{\text{xy}}$

Kết quả của tổng $\frac{\text{a}-\text{2}}{\text{a}-\text{b}}+\frac{\text{b}-\text{2}}{\text{b}-\text{a}}$  là?

A. -1

B. 1

C. $\frac{\text{a}-\text{b}}{\text{b}-\text{a}}$

D. $\frac{\text{a}+\text{b}-\text{4}}{\text{a}-\text{b}}$

Biểu thức x - 2 là kết quả của phép tính nào dưới đây?

A. $\frac{{\text{x}}^{\text{2}}+\text{4}}{\text{x}-\text{2}}-\frac{\text{4x}}{\text{2}-\text{x}}$

B. $\frac{{\text{x}}^{\text{2}}+\text{4}}{\text{x}-\text{2}}+\frac{\text{4x}}{\text{2}-\text{x}}$

C. $\frac{\text{2x}}{\text{x}-\text{2}}+\frac{\text{4}}{{\text{x}}^{\text{2}}-\text{4}}$

D. $\frac{\text{x}}{\text{x}-\text{2}}+\frac{\text{2}}{\text{x-2}}$

Phân thức $\frac{x - 1}{x + 1}$  là kết quả của phép tính nào dưới đây?

A. $\frac{\text{x}}{\text{x}+\text{1}}-\frac{\text{2}}{\text{x}+\text{1}}$

B. $\frac{\text{2x}}{\text{x}+\text{1}}-\frac{\text{2}}{\text{x}+\text{1}}$

C. $\frac{\text{x}}{\text{x}-\text{1}}+\frac{\text{1}}{\text{x}-\text{1}}$

D. $\frac{\text{x}}{\text{x}+\text{1}}+\frac{\text{1}}{\text{-x}-\text{1}}$

Thực hiện phép tính sau: $\frac{{\text{x}}^{\text{3}}}{{\text{x}}^{\text{2}}+\text{1}}+\frac{\text{x}}{{\text{x}}^{\text{2}}+\text{1}}$

A. -x

B. 2x

C. $\frac{x}{2}$

D. x

Kết quả thu gọn nhất của tổng $\frac{\text{2}-\text{3x}}{{\text{6x}}^{\text{2}}\text{y}}+\frac{\text{2x}+\text{1}}{{\text{6x}}^{\text{2}}\text{y}}+\frac{\text{2x}-\text{3}}{{\text{6x}}^{\text{2}}\text{y}}$  là?

A. $\frac{-\text{1}}{\text{6xy}}$

B. $\frac{\text{1}}{{\text{6x}}^{\text{2}}\text{y}}$

C. $\frac{\text{1}}{\text{6xy}}$

D. $\frac{\text{x}}{\text{6xy}}$

Phân thức đối của phân thức $\frac{-\text{x}}{\text{x}-\text{1}}$  là?

A. $\frac{\text{x}}{\text{x}-\text{1}}$

B. $\frac{\text{x}-\text{1}}{-\text{x}}$$\frac{-\text{x}}{-\text{x}-\text{1}}$

C. $\frac{-\text{x}}{-\text{x}-\text{1}}$

D. $\frac{\text{x}}{-\text{x}+\text{1}}$

Phân thức đối của phân thức $\frac{\text{3}}{\text{x}+\text{1}}$  là?

A. $\frac{-\text{3}}{\text{x}+\text{1}}$

B. $\frac{\text{x}+\text{1}}{\text{3}}$

C. $\frac{-\text{3}}{-\text{x}-\text{1}}$

D. $\frac{-\text{3}}{\text{x}-\text{1}}$

Chọn khẳng định đúng?

A. $\frac{\text{A}}{\text{B}}-\frac{\text{C}}{\text{D}}=\frac{\text{A}-\text{C}}{\text{B}-\text{D}}$

B. $\frac{\text{A}}{\text{B}}-\frac{\text{C}}{\text{D}}=\frac{\text{AD}}{\text{BC}}$

C. $\frac{\text{A}}{\text{B}}-\frac{\text{C}}{\text{D}}=\frac{\text{A}}{\text{B}}+\frac{-\text{C}}{\text{D}}$

D. $\frac{\text{A}}{\text{B}}-\frac{\text{C}}{\text{D}}=\frac{\text{A}-\text{C}}{\text{BD}}$

Với B ≠ 0, kết quả phép cộng $\frac{\text{A}}{\text{B}}+\frac{\text{C}}{\text{B}}$  là?

A. $\frac{\text{A.C}}{\text{B}}$

B. $\frac{\text{A+C}}{\text{B}}$

C. $\frac{\text{A+C}}{{\text{B}}^2}$

D. $\frac{\text{A+C}}{\text{2B}}$

Cho các phân thức $\frac{\text{1}}{\text{(a}-\text{b)(b}-\text{c)}}\text{;}\frac{\text{1}}{\text{(c}-\text{b)(c}-\text{a)}}\text{;}\frac{\text{1}}{\text{(b}-\text{a)(a}-\text{c)}}$ .

Bạn Mai nói rằng mẫu thức chung của các phân thức trên là (a - b)(b - c)(a - c).

Bạn Nhung nói rằng mẫu thức chung của các phân thức trên là (b - a)(c - b)(c - a).

Chọn câu đúng?

A. Bạn Mai đúng, bạn Nhung sai.

B. Bạn Mai sai, bạn Nhung đúng.

C. Hai bạn đều sai.

D. Hai bạn đều đúng.

Cho các phân thức $\frac{\text{11x}}{\text{3x}-\text{3}}\text{;}\frac{\text{5}}{\text{4}-\text{4x}}\text{;}\frac{\text{2x}}{{\text{x}}^{\text{2}}-\text{1}}$ .

Bạn Nam nói rằng mẫu thức chung của các phân thức trên là $6(x - 1){(x + 1)}^2$.

Bạn Minh nói rằng mẫu thức chung của các phân thức trên là 4(x - 1)(x + 1)

Chọn câu đúng?

A. Bạn Nam đúng, bạn Minh sai.

B. Bạn Nam sai, bạn Minh đúng.

C. Hai bạn đều sai

D. Hai bạn đều đúng.

Để có các phân thức có cùng mẫu, ta cần điền vào các chỗ trống $\frac{\text{x}+\text{3}}{{\text{x}}^{\text{2}}+\text{8x}+\text{15}}=\frac{\text{x}-\text{3}}{\mathrm{...}}\text{;}\frac{\text{5x}-\text{15}}{{\text{x}}^{\text{2}}-\text{6x}+\text{9}}=\frac{\mathrm{...}}{\text{(x}-\text{3)(x}+\text{5)}}$ các đa thức lần lượt là?

A. x - 3; 5x + 10

B. ${(x - 3)}^2(x + 5); 5x - 25$

C. (x - 3)(x + 5); 5x + 25

D. (x - 3)(x + 5); x + 5

Để có các phân thức có cùng mẫu, ta cần điền vào các chỗ trống $\frac{\text{x}-\text{1}}{{\text{x}}^{\text{2}}\text{(x}+\text{1)}}=\frac{\text{x}-\text{1}}{\mathrm{...}}\text{;}\frac{\text{3x}}{\text{x}+\text{1}}=\frac{\mathrm{...}}{{\text{x}}^{\text{2}}\text{(x}+\text{1)}}$ các đa thức lần lượt là?

A. $x^2(x + 1); 3x^3$

B. $x(x + 1); 3x^2$

C. $x(x - 1); 3x^2$

D. $x + 1; 3x^3$

Cho $\frac{\text{4}}{{\text{x}}^{\text{2}}+\text{3x}+\text{2}}=\frac{\mathrm{...}}{\text{(x}+\text{1)(x}+{\text{2)}}^{\text{2}}}\text{;}\frac{\text{3x}}{{\text{x}}^{\text{2}}+\text{4x}+\text{4}}=\frac{\mathrm{...}}{\text{(x}+\text{1)(x}+{\text{2)}}^{\text{2}}}$ . Điền vào chỗ trống để được các phân thức có cùng mẫu. Hãy chọn câu đúng?

A. $8x + 8; 3x^2 + 3$

B. $4x + 8; 3x^2 + 3x$

C. $8x + 1; 3x^2 + x$

D. $4x + 4; 3x^2 + 3x$

Cho $\frac{\text{2}}{\text{x}+\text{2}}=\frac{\mathrm{...}}{{\text{2x}}^{\text{2}}+\text{4x}}\text{;}\frac{\text{1}}{\text{2x}}=\frac{\mathrm{...}}{{\text{2x}}^{\text{2}}+\text{4x}}$ . Điền vào chỗ trống để được các phân thức có cùng mẫu. Hãy chọn câu đúng?

A. 4x; x + 2

B. 2x; x + 2

C. 4x; x + 1

D. $4x^2; x + 2$

Cho ba phân thức $\frac{\text{3}}{{\text{5x}}^{\text{2}}\text{yz}}\text{,}\frac{\text{5}}{{\text{4y}}^{\text{2}}\text{z}}\text{,}\frac{\text{6}}{{\text{xz}}^{\text{2}}}$ . Chọn khẳng định đúng?

A. $\frac{\text{3}}{{\text{5x}}^{\text{2}}\text{yz}}=\frac{\text{12yz}}{{\text{20x}}^{\text{2}}{\text{y}}^{\text{2}}{\text{z}}^{\text{2}}}\text{;}\frac{\text{5}}{{\text{4y}}^{\text{2}}\text{z}}=\frac{{\text{25x}}^{\text{2}}\text{z}}{{\text{20x}}^{\text{2}}{\text{y}}^{\text{2}}{\text{z}}^{\text{2}}}\text{;}\frac{\text{6}}{{\text{xz}}^{\text{2}}}=\frac{{\text{120x}}^{\text{2}}\text{y}}{{\text{20x}}^{\text{2}}{\text{y}}^{\text{2}}{\text{z}}^{\text{2}}}$

B. $\frac{\text{3}}{{\text{5x}}^{\text{2}}\text{yz}}=\frac{\text{12yz}}{{\text{20x}}^{\text{2}}{\text{y}}^{\text{2}}{\text{z}}^{\text{2}}}\text{;}\frac{\text{5}}{{\text{4y}}^{\text{2}}\text{z}}=\frac{{\text{25x}}^{\text{2}}\text{z}}{{\text{20x}}^{\text{2}}{\text{y}}^{\text{2}}{\text{z}}^{\text{2}}}\text{;}\frac{\text{6}}{{\text{xz}}^{\text{2}}}=\frac{{\text{x}}^{\text{2}}\text{y}}{{\text{20x}}^{\text{2}}{\text{y}}^{\text{2}}{\text{z}}^{\text{2}}}$

C. $\frac{\text{3}}{{\text{5x}}^{\text{2}}\text{yz}}=\frac{\text{3yz}}{{\text{x}}^{\text{2}}{\text{y}}^{\text{2}}{\text{z}}^{\text{2}}}\text{;}\frac{\text{5}}{{\text{4y}}^{\text{2}}\text{z}}=\frac{{\text{5x}}^{\text{2}}\text{z}}{{\text{x}}^{\text{2}}{\text{y}}^{\text{2}}{\text{z}}^{\text{2}}}\text{;}\frac{\text{6}}{{\text{xz}}^{\text{2}}}=\frac{{\text{x}}^{\text{2}}\text{y}}{{\text{x}}^{\text{2}}{\text{y}}^{\text{2}}{\text{z}}^{\text{2}}}$

D. $\frac{\text{3}}{{\text{5x}}^{\text{2}}\text{yz}}=\frac{\text{3yz}}{{\text{20x}}^{\text{2}}{\text{y}}^{\text{2}}{\text{z}}^{\text{2}}}\text{;}\frac{\text{5}}{{\text{4y}}^{\text{2}}\text{z}}=\frac{{\text{20x}}^{\text{2}}\text{z}}{{\text{20x}}^{\text{2}}{\text{y}}^{\text{2}}{\text{z}}^{\text{2}}}\text{;}\frac{\text{6}}{{\text{xz}}^{\text{2}}}=\frac{{\text{120x}}^{\text{2}}\text{y}}{{\text{20x}}^{\text{2}}{\text{y}}^{\text{2}}{\text{z}}^{\text{2}}}$

Cho ba phân thức $\frac{\text{1}}{\text{xy}}\text{,}\frac{\text{1}}{\text{yz}}\text{,}\frac{\text{3}}{\text{xz}}$ . Chọn khẳng định đúng?

A. $\frac{\text{1}}{\text{xy}}=\frac{\text{z}}{\text{xyz}}\text{,}\frac{\text{1}}{\text{yz}}=\frac{\text{x}}{\text{xyz}}\text{,}\frac{\text{3}}{\text{xz}}=\frac{\text{3}}{\text{xyz}}$

B. $\frac{\text{1}}{\text{xy}}=\frac{\text{z}}{\text{xyz}}\text{,}\frac{\text{1}}{\text{yz}}=\frac{\text{x}}{\text{xyz}}\text{,}\frac{\text{3}}{\text{xz}}=\frac{\text{3y}}{\text{xyz}}$

C. $\frac{\text{1}}{\text{xy}}=\frac{\text{z}}{\text{xyz}}\text{,}\frac{\text{1}}{\text{yz}}=\frac{\text{1}}{\text{xyz}}\text{,}\frac{\text{3}}{\text{xz}}=\frac{\text{3y}}{\text{xyz}}$

D. $\frac{\text{1}}{\text{xy}}=\frac{\text{1}}{\text{xyz}}\text{,}\frac{\text{1}}{\text{yz}}=\frac{\text{x}}{\text{xyz}}\text{,}\frac{\text{3}}{\text{xz}}=\frac{\text{3y}}{\text{xyz}}$

Quy đồng mẫu thức các phân thức $\frac{\text{1}}{{\text{x}}^{\text{3}}+\text{1}}\text{;}\frac{\text{2}}{\text{3x}+\text{3}}\text{;}\frac{\text{x}}{{\text{2x}}^{\text{2}}-\text{2x}+\text{2}}$  ta được các phân thức lần lượt là?

A. $\frac{\text{1}}{{\text{x}}^{\text{3}}+\text{1}}\text{;}\frac{{\text{x}}^{\text{2}}-\text{x}+\text{1}}{{\text{3(x}}^{\text{3}}+\text{1)}}\text{;}\frac{{\text{x}}^{\text{2}}+\text{x}}{{\text{2(x}}^{\text{3}}+\text{1)}}$

B. $\frac{\text{1}}{{\text{6(x}}^{\text{3}}+\text{1)}}\text{;}\frac{{\text{x}}^{\text{2}}-\text{x}+\text{1}}{{\text{3(x}}^{\text{3}}+\text{1)}}\text{;}\frac{{\text{3x}}^{\text{2}}+\text{3x}}{{\text{6(x}}^{\text{3}}+\text{1)}}$

C. $\frac{\text{6}}{{\text{6(x}}^{\text{3}}+\text{1)}}\text{;}\frac{{\text{4x}}^{\text{2}}-\text{4x}+\text{4}}{{\text{6(x}}^{\text{3}}+\text{1)}}\text{;}\frac{{\text{3x}}^{\text{2}}+\text{3x}}{{\text{6(x}}^{\text{3}}+\text{1)}}$

D. $\frac{{\text{3x}}^{\text{2}}+\text{3x}}{{\text{6(x}}^{\text{3}}+\text{1)}}\text{;}\frac{{\text{4x}}^{\text{2}}-\text{4x}+\text{4}}{{\text{6(x}}^{\text{3}}+\text{1)}}\text{;}\frac{\text{6}}{{\text{6(x}}^{\text{3}}+\text{1)}}$

Quy đồng mẫu thức của các phân thức $\frac{\text{x}-\text{2}}{\text{3(x}-\text{1)}}\text{,}\frac{\text{5}}{\text{2(x}+\text{1)}}\text{,}\frac{\text{x}+\text{3}}{{\text{x}}^{\text{2}}-\text{1}}$  ta được:

A. $\frac{\text{x}-\text{2}}{\text{3(x}-\text{1)}}=\frac{\text{2(x}-\text{2)(x}+\text{1)}}{{\text{6(x}}^{\text{2}}-\text{1)}}\text{,}\frac{\text{5}}{\text{2(x}+\text{1)}}=\frac{\text{5(x}+\text{1)}}{{\text{6(x}}^{\text{2}}-\text{1)}}\text{,}\frac{\text{x}+\text{3}}{{\text{x}}^{\text{2}}-\text{1}}=\frac{\text{2(x}+\text{3)}}{{\text{6(x}}^{\text{2}}-\text{1)}}$

B. $\frac{\text{x}-\text{2}}{\text{3(x}-\text{1)}}=\frac{\text{2(x}-\text{2)}}{{\text{6(x}}^{\text{2}}-\text{1)}}\text{,}\frac{\text{5}}{\text{2(x}+\text{1)}}=\frac{\text{15(x}-\text{1)}}{{\text{6(x}}^{\text{2}}-\text{1)}}\text{,}\frac{\text{x}+\text{3}}{{\text{x}}^{\text{2}}-\text{1}}=\frac{\text{6(x}+\text{3)}}{{\text{6(x}}^{\text{2}}-\text{1)}}$

C. $\frac{\text{x}-\text{2}}{\text{3(x}-\text{1)}}=\frac{\text{2(x}-\text{2)(x}+\text{1)}}{{\text{6(x}}^{\text{2}}-\text{1)}}\text{,}\frac{\text{5}}{\text{2(x}+\text{1)}}=\frac{\text{15(x}-\text{1)}}{{\text{6(x}}^{\text{2}}-\text{1)}}\text{,}\frac{\text{x}+\text{3}}{{\text{x}}^{\text{2}}-\text{1}}=\frac{\text{6}}{{\text{6(x}}^{\text{2}}-\text{1)}}$

D. $\frac{\text{x}-\text{2}}{\text{3(x}-\text{1)}}=\frac{\text{2(x}-\text{2)(x}+\text{1)}}{{\text{6(x}}^{\text{2}}-\text{1)}}\text{,}\frac{\text{5}}{\text{2(x}+\text{1)}}=\frac{\text{15(x}-\text{1)}}{{\text{6(x}}^{\text{2}}-\text{1)}}\text{,}\frac{\text{x}+\text{3}}{{\text{x}}^{\text{2}}-\text{1}}=\frac{\text{6(x}+\text{3)}}{{\text{6(x}}^{\text{2}}-\text{1)}}$