cos^(2) x +2cosxsinx + sin^2x

tan^(4) x - 2tan^x -3

2cos^(2) x - 5cosx + 2

Have a final tomorrow, please dont just start the problem. I would really appreciate it if you could show me the step by step process to any one of these problems. Thanks

2. Originally Posted by acherucheril
cos^(2) x +2cosxsinx + sin^2x

tan^(4) x - 2tan^x -3

2cos^(2) x - 5cosx + 2

Have a final tomorrow, please dont just start the problem. I would really appreciate it if you could show me the step by step process to any one of these problems. Thanks
Sorry, but we're not going to do your work for you.

In the first one, replace $\displaystyle \cos{x}$ with $\displaystyle X$ and $\displaystyle \sin{x}$ with $\displaystyle Y$ to get

$\displaystyle \cos^2{x} + 2\cos{x}\sin{x} + \sin^2{x} = X^2 + 2XY + Y^2$.

Does this look easier to factorise?

Are you sure the second one isn't

$\displaystyle \tan^4{x} - 2 \tan^2{x} - 3$?

The third one, replace $\displaystyle \cos{x}$ with $\displaystyle X$ to get

$\displaystyle 2\cos^2{x}-5\cos{x}+ 2 = 2X^2 - 5X + 2$.

Does this look easier to factorise?