0580/11 Oct/Nov 2025, Question 23: Index Laws with Letters
Cambridge IGCSE Mathematics 0580 · Paper 11 (Core) · Non-calculator · 2 marks
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The question, in short
Using index laws, find the unknown exponent in two equations: a⁸ × aˣ = a¹⁵ and (b⁷)ʸ = b²¹.
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Part (a) · 1 mark
Find x so that a⁸ × aˣ equals a¹⁵.
- 18 + x = 15, so x = 7
Answer7
Part (b) · 1 mark
Find y so that (b⁷)ʸ equals b²¹.
- 17y = 21, so y = 3
Answer3
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Also searched as: 0580/11/O/N/25 · 0580_w25_qp_11 · 0580 w25 11 · question 23.
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