Đáp án:
Giải thích các bước giải:
$1. 5x^2-7x=0$
$(=)x(5x-7)=0$
(=)\(\left[ \begin{array}{l}x=0\\5x-7=0\end{array} \right.\)
(=)\(\left[ \begin{array}{l}x=0\\x=\dfrac{7}{5}\end{array} \right.\)
$2. 2x^2=3x$
$(=)2x^2-3x=0$
$(=)x(2x-3)=0$
(=)\(\left[ \begin{array}{l}x=0\\2x-3=0\end{array} \right.\)
(=)\(\left[ \begin{array}{l}x=0\\x=\dfrac{3}{2}\end{array} \right.\)
$3. 5(3-x)-6+2x=0$
$(=)15-5x-6+2x=0$
$(=)9-3x=0$
$(=)3x=9$
$(=)x=3$
$4. 4x^2-9x=0$
$(=)x(4x-9)=0$
(=)\(\left[ \begin{array}{l}x=0\\4x-9=0\end{array} \right.\)
(=)\(\left[ \begin{array}{l}x=0\\x=\dfrac{4}{9}\end{array} \right.\)
$5. x^2+5x-6=0$
$(=)x^2-x+6x-6=0$
$(=)(x+6)(x-1)=0$
(=)\(\left[ \begin{array}{l}x+6=0\\x-1=0\end{array} \right.\)
(=)\(\left[ \begin{array}{l}x=-6\\x=1\end{array} \right.\)
$6. x^2+5x+4=0$
$(=)(x+1)(x+4)=0$
(=)\(\left[ \begin{array}{l}x+1=0\\x+4=0\end{array} \right.\)
(=)\(\left[ \begin{array}{l}x=-1\\x=-4\end{array} \right.\)
$7. 2x^2-9x+7=0$
$(=)(2x-7)(x-1)=0$
(=)\(\left[ \begin{array}{l}2x-7=0\\x-1=0\end{array} \right.\)
(=)\(\left[ \begin{array}{l}x=\dfrac{7}{2}\\x=1\end{array} \right.\)
$8. 2x^2-9x-11=0$
$(=)(2x-11)(x+1)=0$
(=)\(\left[ \begin{array}{l}2x-11=0\\x+1=0\end{array} \right.\)
(=)\(\left[ \begin{array}{l}x=\dfrac{11}{2}\\x=-1\end{array} \right.\)
$9. 5x^3-6x^2-11x=0$
$(=)x(5x^2-6x-11)=0$
$(=)x(5x-11)(x+1)=0$
(=)\(\left[ \begin{array}{l}x=0\\5x-11=0\\x+1=0\end{array} \right.\)
(=)\(\left[ \begin{array}{l}x=0\\x=\dfrac{11}{5}\\x=-1\end{array} \right.\)
Chúc bạn học tốt.
