Question

Solve the quadratic equation x2+8x−30=0 by completing the square.

Answer 1

Answer:

               $\bold{x=-4\pm\sqrt{46}}$

Step-by-step explanation:

$(a+b)^2=a^2+2ab+b^2\\\\\\x^2+8x-30=0\\\\\underbrace{x^2+2\cdot x\cdot 4+4^2}-4^2-30=0\\\\{}\qquad(x+4)^2\,-\,16-30=0\\\\{}\qquad\ \ (x+4)^2=46\\\\ {}\qquad\ \ x+4=\pm\sqrt{46}\\\\ {}\qquad\ \ x=-4\pm\sqrt{46}$