Search our library of homework questions

Top answers

All subjects

All levels

Use the double angle formulae and the identity cos(A+B)≡cos(A)cos(B)−sin(A)sin(B) to obtain an expression for cos 3x in terms of cos x only

To answer, you need to know and be able to use your trigonometric formulae including the double angle formulae on data sheet.

1: cos(3x)=cos(2x+x) = cos(2x)cos(x) - sin(2x)sin(x) split the 3...

Answered by Sam H. • Maths tutor

17165 Views

Explain why increasing the temperature of a reaction increases the rate of the reaction (2)

By raising the temperature of the reaction mixture, the particles have more (kinetic) energy and so move around at a greater rate. This means there are more frequent collisions, due to the increased speed...

Answered by Sam H. • Chemistry tutor

2803 Views

(2x+3)/(x-4) - (2x-8)/(2x+1) = 1 Solve for x

Multiply out the denominator, take care to multiply both sides of the equation:

(2x+3)(2x+1) - (2x-8)(x-4) = (2x+1)(x-4)

Expand the brackets, pay attention the the signs when multiplying, ex...

Answered by Lucy M. • Maths tutor

3395 Views

How are different substances transported across the cell membrane?

There are several different ways substances can be transported:

1) simple diffusion, i.e. substances that tend to be lipid soluble/ non-polar and can pass easily across the phospholipid bilyar of c...

Answered by Vinay S. • Biology tutor

9803 Views

There are n sweets in a bag, 6 of which are red. The rest of the sweets are blue. Jen removes 1 sweet from the bag. Jen then takes another sweet from the bag. The probability that Hannah takes two red sweets is 1/3. Show that n²-n-90=0.

We know the total number of sweets is n, and that 6 are red. When Jen takes the first sweet, the probability of it being red is [number of red sweets] / [how many there are] = 6/n . For the second sweet, ...

Answered by Amy B. • Maths tutor

4879 Views