Question

In don't understand how to work this problem out

Answer 1

$x^2+8x-11=\\ x^2+8x+16-27=\\ (x+4)^2-27=\\ (x+4-\sqrt{27})(x+4+\sqrt27)=\\ (x+4-3\sqrt{3})(x+4+3\sqrt3)$

$x^2+6x-11=\\ x^2+6x+9-20=\\ (x+3)^2-20=\\ (x+3-\sqrt{20})(x+3+\sqrt{20})=\\ (x+3-2\sqrt5)(x+3+2\sqrt5)$