Question

The square of a certain number plus ten is equal to 81​

Answer 1

Answer:

x = ±8.43 (to 3sf)

Step-by-step explanation:

Let this number be x.

x² + 10 = 81

      x² = 81 - 10

           = 71

        x = ±√71

           = ±8.43 (to 3sf)