a) 3(2x – 3) + 2(2 – x) = –3;
b) x(5 – 2x) + 2x(x – 1) = 13;
c) 5x(x – 1) – (x + 2)(5x – 7) = 6;
d) 3x(2x + 3) – (2x + 5)(3x – 2) = 8 ;
e) 2(5x – 8) – 3(4x – 5) = 4(3x – 4) + 11;
f) 2x(6x – 2x2) + 3x2(x – 4) = 8.
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3 câu trả lời 288
`a,3.(2x-3)+2.(2-x)=3`
`<=>6x-9+4-2x=3`
`<=>6x-2x=3+9-4`
`<=>4x=8`
`<=>x=2`
Vậy `S={2}`
`b,x.(5-2x)+2x.(x-1)=13`
`<=>5x-2x^2+2x^2-2x=13`
`<=>2x^2-2x^2+5x-2x=13`
`<=>3x=13`
`<=>x=13/3`
Vậy `S={13/3}`
`c,5x(x-1)-(x+2)(5x-7)=6`
`<=>5x^2-5x-(5x^2-7x+10x-14)=6`
`<=>5x^2-5x-5x^2+7x-10x+14=6`
`<=>7x-5x-10x=6-14`
`<=> -8x=-8`
`<=>x=1`
Vậy `S={1}`
`\color{red}{\text{d)}}`
`3x(2x+3)-(2x+5)(3x-2)=8`
`<=>` `6x^2+9x-(6x^2-4x+15x-10)=8`
`<=>` `6x^2+9x-6x^2+4x-15x+10=8`
`<=>` `-2x+10=8`
`<=>` `-2x=-2`
`<=>` `x=1`
Vậy `x=1`
`\color{red}{\text{e)}}`
`2(5x-8)-3(4x-5)=4(3x-4)+11`
`<=>` `10x-16-12x+15=12x-16+11`
`<=>` `10x-12x-12x=-16+11+16-15`
`<=>` `-14x=-4`
`<=>` `x=2/7`
Vậy `x=2/7`
`\color{red}{\text{f)}}`
`2x(6x-2x^2)+3x^2(x-4)=8`
`<=>` `12x^2-4x^3+3x^3-12x^2=8`
`<=>` `-x^3=8`
`<=>` `x^3=-(2^3)`
`<=>` `x=-2`
Vậy `x=-2`
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