Quadratic Equations?

Question

How would you solve this and can you give me step by step instructions using the quadractic formula, thanks.

x²-2x-10=0

Answer 1

The quadratic formula is the following:

x = [-b (+/-) sqrt(b² - 4ac)] / (2a)

You can use this formula whenever the equation is in this form: ax² + bx + c = 0.

So in your problem, a = 1, b = -2, and c = -10.

Plug these values into the equation:

x = [-(-2) (+/-) sqrt((-2)² - (4*1*-10))] / (2 * 1).  Simplify:

x = [2 (+/-) sqrt(4 + 40)] / 2

x = [2 (+/-) sqrt(44)] / 2

x = [2 (+/-) sqrt(4 * 11)] / 2

x = [2 (+/-) 2sqrt(11)] / 2.  Factor out 2 from the numerator:

x = (2[1 (+/-) sqrt(11)]) / 2.  The 2s cancel out:

x = 1 (+/-) sqrt(11)

x = 1 + sqrt(11), 1 - sqrt(11)

x = 4.32, -2.32

Hope that helped!