Search our library of A Level questions

Top answers

All subjects

A Level

Express cos5x in terms of increasing powers of cosx

De Moivre's theorem: (cos5x + isin5x) = (cosx + isinx)⁵ To get cos5x we will need to expand (cosx + isinx)⁵ and then take the real parts. Binomial expansion: (cosx + isinx)⁵

Answered by Chris S. • Further Mathematics tutor

34553 Views

Integrate cos(2x)

The intergral for cosx is sinx, but '2x' must be considered.

When differentiating a sinx/cosx function, the '2x' would be differentiated separately

and placed in the front (multipling). So w...

Answered by Gold O. • Maths tutor

18456 Views

What is the best way to approach analysing a historical source?

Firstly it is important to cover the who, what, when and where of the source to gain a better understanding. Next, the content of the source should be picked apart to find the true point of it. This shoul...

Answered by Jessica V. • History tutor

2507 Views

How do you solve the equation e^2x - 2e^x - 3 = 0 ?

This is a 'quadratic in e^x'. The easiest way to recognise this when starting problems like this is to let y=e^x. As you practice problems like this, you will find yourself moving away from this step. But...

Answered by Lewis C. • Maths tutor

15245 Views