Đáp án: `a)` `x = -7`
`b)` `x=4`
`c)` \(\left[ \begin{array}{l}x=3\\x=-11/10\end{array} \right.\)
Giải thích các bước giải:
`a, (2x+1)(x-3)-x(2x-3)=11`
`<=> 2x^2-5x-3-2x^2+3x=11`
`<=> 3x-5x=11+3;` `<=> -2x=14` `<=> x=-7`
.
`b, 3(x-2)(x+5)=3(x-1)(x+2)`
`<=> (x-2)(x+5)=(x-1)(x+2)`
`<=>x^2+3x-10= x^2+x-2` `<=>3x-x=10 -2`
`<=>2x=8` `<=>x=4`
.
`c, (8x-3)(3x+2)-(4x+7)(x+4)=(2x+1)(5x-1)`
`<=> 24x^2+7x-6-(4x^2+23x+28)=10x^2+3x-1`
`<=> 24x^2+7x-6-4x^2-23x-28=10x^2+3x-1`
`<=> 20x^2-16x-34=10x^2+3x-1` `<=> 10x^2-19x-33=0`
`<=> 10x^2+11x-30x-33=0` `<=> x.(10x+11)-3.(10x+11)=0`
`<=> (x-3)(10x+11)=0`
`<=>`\(\left[ \begin{array}{l}x-3=0\\10x+11=0\end{array} \right.\) `<=>`\(\left[ \begin{array}{l}x=3\\x=-11/10\end{array} \right.\)
