Solve: 16x2 − 81 = 0.
x = 4, 9
x = −4, −9
x = 9 over 4, x = −9 over 4
x = 81 over 16, x = −81 over 16

If you would like to solve 16x^2 - 81 = 0, you can calculate this using the following steps:

16x^2 - 81 = 0
(4x - 9) * (4x + 9) = 0
1. 4x - 9 = 0 ... 4x = 9 ... x = 9/4
2. 4x + 9 = 0 ... 4x = - 9 ... x = - 9/4

The correct result would be: x = 9 over 4, x = −9 over 4. 

Answer might be d.i think