# Thread: Simple Differentiation (checking i'm right)

1. ## Simple Differentiation (checking i'm right)

Hi,

I'm just doing a past paper but i don't have the mark scheme would anyone be kind enough to double check my answer:

Question: Differentiate $(e^x)/(sin(x) + cos(x))$

MyAnswer: $(e^x(sin(x) + cos(x)) + e^x(cos(x) - sin(x)))/((sin(x) + cos(x))^2)$

2. Seems correct, you can also simplify this

3. Argh dam it i thought you might be able to - i can't for the life of me see where but it just 'looks' like it should? Could you start me off?

4. Well for starters in the denominator when you multiply the term
${(sin(x)+cos(x))}^2$
You can remember the identity $sin(x)^2+cos(x)^2 = 1$

5. Originally Posted by aceband and reformatted by Mr F
Hi,

I'm just doing a past paper but i don't have the mark scheme would anyone be kind enough to double check my answer:

Question: Differentiate $\frac{e^x}{\sin(x) + \cos(x)}$

MyAnswer: $\frac{e^x(\sin(x) + \cos(x)) {\color{red}+} e^x(\cos(x) - \sin(x))}{(\sin(x) + \cos(x))^2}$
The red plus should be a minus.

There is a common factor in the numerator which leads to considerable simplification (after you fix the mistake). I'd leave the denominator as it is.