Substitution Flashcards

GCSE Mathematics (Edexcel) 1MA1

Substitution

The process of replacing variables in an expression or equation with specific values.

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Terms in this set (10)

1

Substitution

The process of replacing variables in an expression or equation with specific values.

2

Evaluate 3x + 2 when x = 4

Substitute x = 4 into the expression: 3(4) + 2 = 12 + 2 = 14.

3

Substitute into a formula

Replace the variables in a formula with given values to calculate the result.

4

Example: Find the value of y = 2x - 5 when x = 3

Substitute x = 3: y = 2(3) - 5 = 6 - 5 = 1.

5

Substitution into quadratic expressions

Replace the variable in a quadratic expression (e.g., x² + 3x - 4) with a given value and simplify.

6

Evaluate x² - 4x + 7 when x = -2

Substitute x = -2: (-2)² - 4(-2) + 7 = 4 + 8 + 7 = 19.

7

Substitution into formulae with multiple variables

Replace each variable in the formula with its given value and simplify step by step.

8

Example: Find the value of A = 2b + c when b = 3 and c = 5

Substitute b = 3 and c = 5: A = 2(3) + 5 = 6 + 5 = 11.

9

Common mistake in substitution

For negative values, always use brackets when substituting into expressions, especially with powers.

10

Substitute into a real-life formula: Speed = Distance ÷ Time

If Distance = 150 km and Time = 3 hours, Speed = 150 ÷ 3 = 50 km/h.

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