Which is a solution to (x − 2)(x + 10) = 13?

x = 3
x = 8
x = 10
x = 11

1. expand the equation
x^2 + 10x -2x -20 = 13

2. Collect like terms
x^2 + 8x - 20 = 13

3. Simplify
x^2 + 8x = 13 + 20
x^2 + 8x = 33
x^2 = 33 - 8x

4. Substitute answers for guess and check
3^2 = 33 - (8 x 3)
9 = 33 - 24

This equation is correct therefore x = 3

1. expand the equation
x^2 + 10x -2x -20 = 13

2. Collect like terms
x^2 + 8x - 20 = 13

3. Simplify
x^2 + 8x = 13 + 20
x^2 + 8x = 33
x^2 = 33 - 8x

4. Substitute answers for guess and check
3^2 = 33 - (8 x 3)
9 = 33 - 24

This equation is correct therefore x = 3