C4 Differentiation help pls

diffing a^x is always ln(a)a^x where 'a' is a constant. so try do it now.

thanks very much ...i never knew this rule..was it present in c3?

nope its in c4 only. remember, sometimes you'd have to apply the chain rule for ones like diffing y=2^(2x), it would be
2ln(2)2^(2x).

C4 EDEXCEL book

Hello , I was a bit stuck on this and thought I would ask for help before starting to break out in tears. thanks for all the help in advance!


how do we differentiate 5^x. in Core 4, one of the question gave the sub (for integration ) to be u=5^x .. But in C3 we never learned any rules as to how to differntiate this ....then how can they expect us to know how to diff this....thanks

Page 50 point 4

(green/blue book)

i am doing a green book and btw pg 50 is on vectors.

If $y=a^x$, then $lny=xlna$. Differentiating both sides gives $\frac{1}{y}.\frac{dy}{dx}=lna$
Multiplying by $y$ then gives $\frac{dy}{dx}=ylna$

And so as $y=a^x, \frac{dy}{dx}=a^xlna$.