Hi there! First we need to add 81 to both sides. 16x2-81+81=0+81=16x2=81. 16x2/16=81/16. Now we get x²=81/16. Now, we have to take the square root. That would be 2.25 or -2.25 it really doesn't matter which answer it is. Therefore, the answer is x=2.25 or x=-2.25.