GCSE Maths Summary

Topic/Skill Definition/Tips
Topic: Equations and Formulae Example
1. Solve To find the answer/value of something Solve 2 x−3=7

Use inverse operations on both sides of Add 3 on both sides
the equation (balancing method) until you 2 x=10
find the value for the letter. Divide by 2 on both sides
x=5

2. Inverse Opposite The inverse of addition is subtraction.
The inverse of multiplication is
division.
3. Rearranging Use inverse operations on both sides of 2 x−1
Make x the subject of y=
Formulae the formula (balancing method) until you z
find the expression for the letter.
Multiply both sides by z
yz=2 x−1
Add 1 to both sides
yz +1=2 x
Divide by 2 on both sides
yz+ 1
=x
2
We now have x as the subject.
4. Writing Substitute letters for words in the Bob charges £3 per window and a £5
Formulae question. call out charge.

C=3 N +5

Where N=number of windows and
C=cost
5. Substitution Replace letters with numbers. a=3 , b=2∧c=5. Find:
1. 2 a=2× 3=6
Be careful of 5 x 2. You need to square first, 2. 3 a−2 b=3 ×3−2 ×2=5
then multiply by 5. 3. 7 b2 −5=7 × 22−5=23




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