Đáp án:
$1)$$S=\{2;\dfrac{-3}{5}\}$
$2)$$S=\{9\}$
Giải thích các bước giải:
$1) 2(x-3)-5x(-1)=5x^2$
$⇔2x-6+5x=5x^2$
$⇔5x^2-7x+6=0$
$⇔x^2-$$\dfrac{7}{5}x-$ $\dfrac{6}{5}=0$
$⇔x^2-$$\dfrac{7}{5}x=$ $\dfrac{6}{5}$
$⇔x^2-$$\dfrac{7}{5}x+\dfrac{49}{100}$= $\dfrac{6}{5}+\dfrac{49}{100}$
$⇔x^2-$$\dfrac{7}{5}x+\dfrac{49}{100}$= $\dfrac{169}{100}$
$⇔\bigg(x-$$\dfrac{7}{10}\bigg)^2=$ $\bigg(\dfrac{13}{10}\bigg)^2$
$⇔x-$$\dfrac{7}{10}= ±\dfrac{13}{10}$
$⇔x= \dfrac{7}{10}±\dfrac{13}{10}$
\(⇔\left[ \begin{array}{l}x=\dfrac{7+13}{10}\\x=\dfrac{7-13}{10}\end{array} \right.\)
\(⇔\left[ \begin{array}{l}x=\dfrac{20}{10}\\x=\dfrac{-6}{10}\end{array} \right.\)
\(⇔\left[ \begin{array}{l}x=2\\x=\dfrac{-3}{5}\end{array} \right.\)
Vậy $S=\{2;\dfrac{-3}{5}\}$
$2)10x+3-5x=4x+12$
$⇔5x+3=4x+12$
$⇔5x-4x=12-3$
$⇔x=9$
Vậy $S=\{9\}$
