In order to make the equation true, the expression in the left side needs to have the same base and exponent of the expression in the right side.
So we have:
[tex](x^4)\cdot(-4^y)=(-12)^4[/tex]
Using the value of y = 4 so we have the same exponents, we have:
[tex]x^4\cdot(-4)^4=(-12)^4[/tex]
Since the exponents are the same, we can multiply the bases and use the same exponent:
[tex]\begin{gathered} (-4x)^4=(-12)^4 \\ -4x=-12 \\ x=3 \end{gathered}[/tex]
So the answer is x = 3 and y = 4
