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Maths Dictionary · JSS 2

Substitution

Simple meaning

Putting numbers in place of letters to work out a value.

Example

If x = 3, then 2x + 5 = 2 × 3 + 5 = 11.

See it

From the Substitution lesson. Try moving things around.

x = −3y = 4

Machine rule

2x2 − 3y

Out: 6
  1. 1Substitute (negatives in brackets)= 2 × (−3)2 − 3 × 4
  2. 2Powers first= 2 × 9 − 3 × 4
  3. 3Multiply, keeping each term's sign= 18 − 12
  4. 4Add and subtract= 6
x−3
y4