Question

If `m^4+n^4=0`, what is the value of `9m - 5n`?

Answer 1

`0`

Explanation:

Assuming we are limiting ourselves to Real values of `m` and `n`, note that for any real number `x`:

`x^4 = (x^2)^2 >= 0`

with equality only when `x=0`

So the only real numbers `m, n` satisfying `m^4+n^4 = 0` are `m=0`, `n=0`.

Hence:

`9m-5n = 0-0=0`