Question

Решите уравнение (x+1)(3x-8)=xв квадрате -5

Answer 1

(x+1)(3x-8)=x²-5
3x²-8x+3x-8-x²+5=0
2x²-5x-3=0
D=b²-4ac=25-4*2*(-3)=25-8*(-3)=25+24=$\sqrt{49}$=7

x₁=$\frac{5+7}{2*2} = \frac{12}{4} =3$

x₂=$\frac{5-7}{2*2} = \frac{-2}{4} = \frac{-1}{2} = -0,5$