Question

Угадайте корень уравнения x(x+8)=105

Answer 1

$x^{2}+8x=105 \\ x^{2}+8x-105=0 \\ D=8^{2}-4*(-105)*1=64+420=484=22^{2}\\ x_{1}= \frac{-8-22}{2}= \frac{-30}{2}=-15\\ x_{2}= \frac{-8+22}{2}= \frac{14}{2}=7$

Answer 2

X(x+8)=105
x^2+8x=105
x=7
7(7+8)=49+56=105