12.

Solve by factoring.

1. Transpose all terms to one side leaving a 0 on the other.

This has already been done

2. Factor

(2x - 5)(x + 2) = 0

3. Set the factors = 0

2x - 5 = 0

x + 2 = 0

4. Solve

2x = 5

x = 5/2

x = -2

5. Check

x = 5/2

2(5/2)2 - (5/2) - 10 = 0

2(25/4) - 5/2 - 10 = 0

25/2 - 5/2 - 10 = 0

20/2 - 10 = 0

10 - 10 = 0

x = -2

2(-2)2 -(-2) - 10 = 0

2(4) + 2 - 10 = 0

8 + 2 - 10 = 0

10 - 10 = 0