Question

What are the roots of the equation: X^2 - 10x -20 =20

1. 10±6√5
2. -10±6√5
3. 5±3√5
4. -5±3√5

Please explain and show work!
Thanks A Bunch!

Answer 1

a = 1  b = -10  c = -20
Using the quadratic formula,
x = [--10 +-sqr root (100 -4*1*-20)] / 2*1
x = [10 +- sqr root (180)] / 2
x = 10/2 +- (sqr root (180) / 2)
x = 5 +- (3 * sqr root (20) / 2)
x = 5 +- (6 * sqr root (5) / 2)
x = 5 +- 3 * sqr root (5)

So the answer is #3