You have written 0 = 4x.
The value of x that makes it true is x = 0, given that 4 times 0 is 0.
Nevertheless, I think you wanted to write 0 = 4 ^x (this is 4 raised to the power 4).
In that case, there is not any valued of x that satisfies the equation. This is, the equation is always false.
That is because, there is not any value of x for which 4^x is zero. The range of this function is al the positive values of x, which exclude zero.
