0580/21 Oct/Nov 2025, Question 17: Rearranging Formulas
Cambridge IGCSE Mathematics 0580 · Paper 21 (Extended) · Non-calculator · 5 marks
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The question, in short
Using the given formula for I, work out its numerical value from supplied values, then make k the subject of the same equation.
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Part (a) · 2 marks
Substitute M = 7, k = 3 and c = 2 into the formula and calculate I.
- 1I = 7(3² + 2²) = 7(9 + 4)
- 2= 7 × 13 = 91
Answer91
Part (b) · 3 marks
Rearrange the equation so that k is expressed using I, M and c.
- 1I/M = k² + c²
- 2k² = I/M − c²
- 3k = ±√(I/M − c²)
Answer±√(I/M − c²) or ±√((I − Mc²)/M)
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Also searched as: 0580/21/O/N/25 · 0580_w25_qp_21 · 0580 w25 21 · question 17.
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