Đáp án + Giải thích các bước giải:
`a)` `3x^2-3x(-2+x)=36`
`<=> 3x^2+6x-3x^2=36`
`<=> 6x=36`
`<=> x=6`
Vậy `x=6`
`b)` `x(5-2x)+2x(x-1)=15`
`<=> 5x-2x^2+2x^2-2x=15`
`<=> 3x=15`
`<=> x=5`
Vậy `x=5`
`c)` `3x(12x-4)-9x(4x-3)=30`
`<=> 36x^2-12x-36x^2+27x=30`
`<=> 15x=30`
`<=> x=2`
Vậy `x=2`
`d)` `(x+1)(3x^2-x+1)+x^2(4-3x)=5/2`
`<=> 3x^3-x^2+x+3x^2-x+1+4x^2-3x^3=5/2`
`<=> 6x^2=5/2-1`
`<=> 6x^2=3/2`
`<=> x^2=1/4`
`<=> x=+-1/2`
Vậy `x=+-1/2`
`e)` `2(x-2)(x+2)+4(x-2)(x+1)+(x+2)(8-5x)=0`
`<=> 2(x^2-4)+4(x^2-x-2)+8x-5x^2+16-10x=0`
`<=> 2x^2-8+4x^2-4x-8-2x-5x^2+16=0`
`<=> x^2-6x=0`
`<=> x.(x-6)=0`
`<=>` \(\left[ \begin{array}{l}x=0\\x-6=0\end{array} \right.\) `<=>`\(\left[ \begin{array}{l}x=0\\x=6\end{array} \right.\)
Vậy `x in {0;6}`
