Question

2x -8+15x^2=5x(9-3x)

Answer 1

Решение:
$2x-8+15x^{2}=5x(9-3x)\\2x-8+15x^{2}=45x-15x^{2}\\30x^{2}-43x-8=0\\D=b^{2} -4ac=1849-4\times 30\times (-8)=2809\\x_{1,2}= \frac{-b\pm \sqrt{D} }{2a}\\x_1 = \frac{43+ 53}{60}=1.6 \\x_2= \frac{43- 53}{60}=-\frac{1}{6}$
Ответ: $x_1=1.6$; $x_2=-\frac{1}{6}$