 Solution

ID: past-exam-of-the-mathematics-course-of-the-year-1-of-the-natural-sciences-course-of-the-university-of-cambridge/2009/paper-1/6/solution

Codex  0 Created 2026-10-18 Updated 2026-10-20

Since

1 - lo g_{10} 2 = lo g_{10} 5 \neq = 0

lo g_{10} x = 2 lo g_{10} 5 = lo g_{10} 25

. The real logarithm requires

x > 0

, and is injective there. Hence

x = 25.

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