Question

x la puterea 2 - x = 72. Cât este x? Va rog... dau coroană!

Answer 1

[tex]x^2-x=72\\ x^2-x-72=0\\ \triangle=b^2-4ac=1+4\cdot 72=289\\ x_{1/2}=\frac{-b\pm\sqrt{\triangle}}{2a}= \frac{1\pm17}{2}\\ x_1= \frac{1+17}{2}=9\\ x_2= \frac{1-17}{2}=-8\\ S=\{-8,9\}[/tex]