(4x+7)^2=60 how to do extracting the square root?

(4x + 7)² = 60
(4x + 7)(4x + 7) = 60
(4x² + 28x + 28x + 49) = 60
4x² + 56x + 49 = 60
                  -49   -49
        4x² + 56x = 11
4x² + 56x - 11 = 11 - 11
4x² + 56x - 11 = 0
x = -56 +/- √(56² - 4(4)(-11))
                     2(4)
x = -56 +/- √(3136 + 88)
                     8
x = -56 +/- √(3174)
                 8
x = -56 +/- 56.34
               8
x = -7 +/- 7.0425
x = -7 + 7.70425       x = -7 - 7.70425
x = 0.70425              x = -14.70425

The last one hope it works