In problem 12, solve by the quadratic formula.

The quadratic Formula says

where

a = 2 |
b = -1 |
and |
c = -10 |

If we substitute these numbers into the quadratic formula we get

This gives us two answers

which are the same as the answers we got when we factored and when we completed the square. For the check, see the end of the discussion on solving this equation by factoring.