Stuck on Khan Academy Math Problem: Structure in Expressions I am having trouble understanding a math problem on Khan Academy even with the explanation they give me. 
The expression:
$$({x^2} + {h^2})({x^2} - {h^2})
$$
can be written as
$$(1 + m - p){x^4} - mp
$$
where h, m, and p are constants what is one possible value of m?
The answer is $${h^2}
$$
I don't understand how they got that. 
I know that:$$\begin{array}{l}({x^2} + {h^2})({x^2} - {h^2}) = ({x^4} - {h^4})\\\end{array}
$$
But when I set equal both equations I get 
$$\begin{array}{l}\frac{{({x^4} - {h^4}) = (1 + m - p){x^4} - mp}}{{{x^4}}} = \\1 - {h^4} = 1 + m - p - mp = \\ - {h^4} = m - p - mp = \\m = {h^4} - p - mp\end{array}
$$
The answer I got was different from the answer KhanAcademy got. 
Can one explain how $h^2$ is the answer and why the answer I got is incorrect.
Thank you so much!

I think it must be $$1+m-p=1$$ and $$mp=h^4$$ solving this we get $$m=\pm h^2$$ and $$p=\pm h^2$$
