Question

Complete the square to transform the quadratic equation into the form

Answer 1

The square of a binomial is written like

$(x\pm a)^2 = x^2\pm 2ax + a^2$

In your case, you have $2ax=-8x$, which implies $a=-4$

So, we want to write

$(x-4)^2 = x^2-8x+16$

But our left hand side is

$x^2-8x-10$

If we add 26 to both sides, we have

$x^2 - 8x - 10 +26 = 18+26 \iff x^2-8x+16=44 \iff (x-4)^2=44$