Paper 1 · Algebra
⏱ Tested in 5 exam questions since 2016
Lesson 19 of 23
Algebra 19 – Simultaneous Equations by substitution
You’ll learn
- Spot when a squared term forces the substitution method over elimination
- Isolate a variable in the linear equation and substitute into the quadratic
- Solve the resulting quadratic and back-substitute for both solution pairs
- Present paired answers as coordinates (x, y)
Formula used
Roots of the quadratic equation
x = (-b ± √(b² − 4ac)) / 2a
On page 20 of the log tables — read it off, don’t memorise.Most recent exam questions
- 2025 P1 Q4(a) — deferred
- 2024 P1 Q1(c) — deferred
- 2022 P1 Q4(a) — deferred
- 2022 P2 Q1(c)
- 2016 P1 Q2(b)
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