(25)7.5 x (5)2.5 ÷ (125)1.5 = 5?
2025
(25)7.5 x (5)2.5 ÷ (125)1.5 = 5?
- A.
8.5
- B.
13
- C.
34
- D.
56
Show answer & explanation
Correct answer: B
Concept: To simplify products and quotients of exponential terms with different bases, first express every base as a power of the same prime base. Then apply the laws of exponents: (am)n = a(mn); am × an = a(m+n); am ÷ an = a(m−n).
25 = 52, so (25)7.5 = (52)7.5 = 515 (since 2 × 7.5 = 15).
125 = 53, so (125)1.5 = (53)1.5 = 54.5 (since 3 × 1.5 = 4.5).
Substituting back: 515 × 52.5 ÷ 54.5 = 5x, so the exponents combine as 15 + 2.5 − 4.5.
15 + 2.5 − 4.5 = 13, so 513 = 5x, giving x = 13.
Cross-check: 15 + 2.5 = 17.5, and 17.5 − 4.5 = 13, so the arithmetic is consistent, confirming x = 13.
