Originally Posted by

**Hellreaver** I need to prove that these determinants are equals.

Note: these are determinants, not matrices, I just don't know how to set them up as determinants using the math code...

$\displaystyle \begin{bmatrix}a1+b1t&a2+b2t&a3+b3t\\a1t+b1&a2t+b2 &a3t+b3\\c1&c2&c3 \end{bmatrix}$ = (1-$\displaystyle t^2$)$\displaystyle \begin{bmatrix}a1&a2&a3\\b1&b2&b3\\c1&c2&c3 \end{bmatrix}$

This tells me that I need to somehow get (1-$\displaystyle t^2$) multiplied into the determinant. I know that to get that out, one would have to multiply a row by (1-$\displaystyle t^2$), or possibly (1-t) on two different rows... Am I thinking it the right direction?