Question 194140
Complete the square:
Take 1/2 of the coefficient of {{{x}}}
square it, and add to both sides
{{{x^2 - 8x + 16 = 0}}}
First, subtract {{{16}}} from both sides
{{{x^2 - 8x = -16}}}
{{{x^2 - 8x (-8/2)^2 = -16 + (-8/2)^2}}}
{{{x^2 - 8x + 16 = -16 + 16}}}
The left side is now a perfect square
{{{(x - 4)^2 = 0}}}
{{{(x - 4)(x - 4) = 0}}}
This has double roots, and for each one,
{{{x = 4}}} which is real, so 2 real roots