c ≈ -6.3, 6.3
c^2 = 40
Square root both sides to find c.
c = √40
Convert √40 to a number using a calculator. This can be positive or negative.
-√40 = -6.32455532
√40 = 6.32455532
Round to the nearest tenth by looking at the value to it's right (the second digit after the decimal place) and rounding up if it's greater than or equal to 5.
-√40 = -6.32455532
√40 = 6.32455532
2 < 5, so we leave it as it is.
c ≈ -6.3, 6.3
