Question 31450
Solve by completing the square:
{{{x^2-4x-5 = 0}}} First add 5 to both sides of the equation.
{{{x^2-4x = 5}}} Now complete the square in the x-terms by adding the square of half the x-coefficient ({{{(4/2)^2 = 4}}})to both sides of the equation.
{{{x^2-4x+4 = 9}}} Now factor the left side.
{{{(x-2)^2 = 9}}} Take the square root of both sides.
{{{x-2 = 3}}}or{{{x-2 = -3}}} So:
{{{x = 5}}} and/or {{{x = -1}}}
The roots are:
{{{x = 5}}}
{{{x = -1}}}