Question 82627
Hi,<br />

You're right. This isn't a quadratic equation. But, we can turn it into one with a simple substitution. If I let *[tex x^2=q] then *[tex x^4=q^2]. Replacing x with q gives:<br />

*[tex q^2-10q+9=0]<br />

This is quadratic in q and can be factorised *[tex (q-1)(q-9)=0]. So we have two solutions for q. But remember *[tex x^2=q]. So for both values of q we have a quadratic in x. Solving these should give you the final answers of x=-3,3,-1,1. If you can't get that, write back and I'll go over the working in more detail.<br />

Hope that helps,
Kev