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This is a simple GCSE question which might feature at the beginning of the paper. It tests the student's attention to detail by asking to find the DIFFERENCE and not just the price that Sue paid. Also, gi...

2x + y = 3   therefore  y = 3 - 2x

Substitute y = 3 - 2x in to the first equation:

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

3x + 6 - 4x = 4

-x = -2   therefore x = 2

Substitute x = 2 in to ei...

To complete the square for the equation ax² + bx + c = 0 there are three steps.. 1. In order to complete the square, we need to take the first two parts of the quadtratic equation, and put them in the for...

Firstly, you need to get rid of any brackets. You do this by expanding them. This becomes 2x + 8 + 6x - 6 = 14.

The next step is to get all the x's on one side, and all the numbers on the other. Yo...

It's impossible to solve an equation with two unknowns (x and y) so we must find a way to get rid of either x or y before solving an equation. Using substitution rearrange the equation 1 so x is the only ...