Đáp án + Giải thích các bước giải:
`a)`
`3x(2x+5)-4x-10=0`
`<=>3x(2x+5)-2(2x+5)=0`
`<=>(2x+5)(3x-2)=0`
`<=>` \(\left[ \begin{array}{l}2x+5=0\\3x-2=0\end{array} \right.\)
`<=>` \(\left[ \begin{array}{l}x=-\dfrac{5}{2}\\x=\dfrac{2}{3}\end{array} \right.\)
`b)`
`12x^{2}-(4x+5)(3x-7)+17=0`
`<=>12x^{2}-(12x^{2}+15x-28x-35)+17=0`
`<=>12x^{2}-(12x^{2}-13x-35)+17=0`
`<=>12x^{2}-12x^{2}+13x+35+17=0`
`<=>13x+52=0`
`<=>13x=-52`
`<=>x=-4`
`c)`
`2x^{2}-3x-9=0`
`<=>(2x^{2}-6x)+(3x-9)=0`
`<=>2x(x-3)+3(x-3)=0`
`<=>(x-3)(2x+3)=0`
`<=>` \(\left[ \begin{array}{l}x-3=0\\2x+3=0\end{array} \right.\)
`<=>` \(\left[ \begin{array}{l}x=3\\x=-\dfrac{3}{2}\end{array} \right.\)
`d)`
`(3x+4)^{2}-(2x-5)^{2}=0`
`<=>(3x+4+2x-5)(3x+4-2x+5)=0`
`<=>(5x-1)(x+9)=0`
`<=>` \(\left[ \begin{array}{l}5x-1=0\\x+9=0\end{array} \right.\)
`<=>` \(\left[ \begin{array}{l}x=\dfrac{1}{5}\\x=-9\end{array} \right.\)
