\( \Large 81^{2.5} \times 9^{4.5} \div 3^{4.8} = 9^{?} \)


A) 7.1

B) 9.4

C) 4.7

D) 4.5

Correct Answer:
A) 7.1

Description for Correct answer:

\( \Large  81^{2.5} \times 9^{4.5} \div 3^{4.8} = 9^{?} \)

=> \( \Large  \frac{81^{2.5} \times 9^{4.5}}{3^{4.8}} = 9^{?} \)

=> \( \Large \frac{ \left(3^{4}\right)^{2.5} \times \left(3^{2}\right)^{4.5} }{3^{4.8}} = 9^{?} \)

=> \(  \Large \frac{3^{10} \times 3^{9}}{3^{4.8}} = 9^{?} \)

=> \(  \Large 3^{10+9-4.8} = 9^{?} \)

=> \( \Large  9^{?} = 3^{14.2} \)

=> \( \Large  \left(3\right)^{2 \times ?} = 3^{14.2} \)

=> \( \Large  2 \times ? = 14.2 \)

Therefore, \( \Large  ? = \frac{14.2}{2} = 7.1 \)


Part of solved Indices and Surd questions and answers : >> Elementary Mathematics >> Indices and Surd








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