Question

Solve the equation using square roots: x2 -81=0

Answer 1

Hi Student!

This question is pretty straight-forward because it is asking for us to solve to equation using square roots. We don't need to find any important information as this problem is pretty simple. We just need to use some algebra to move numbers around and we will get our answer.

Add 81 to both sides

• 
  `x^2 - 81 = 0`

• 
  `x^2 - 81 + 81 = 0 + 81`

• 
  `x^2 = 81`

Square root both sides

• 
  `√(x^2) = √(81)`

• 
  `x = \pm9`

Therefore, after solving for x we were able to determine that the solutions that we have for this equation are both 9 and -9. If we want to test this we can plug in the values into x and we would see that both 9 and -9 would produce the same results as negatives don't matter when we are squaring numbers.