Question

решите уравнение (x-3)(2x+9)=0​

Answer 1

(x-3)*(2x+9)=0

$2x^{2}+9x-6x-27=0$

$2x^{2}+3x-27=0$

$D=b^{2} -4ac$

$D=9+216=225=15^{2}$

$x_{1} =\frac{-3+15}{4}= 3$

$x_{2}=\frac{-3-15}{4} = -4.5$

Или

(x-3)*(2x+9)=0

x-3=0

x=3

2x+9=0

2x= -9

x= -4.5