COMEDK · Maths · 6. Mathematical Induction
\(7^{9}+9^{7}\) is divisible by
- A 128
- B 24
- C 64
- D 72
Answer & Solution
Correct Answer
(C) 64
Step-by-step Solution
Detailed explanation
Now, \(7^{9}=(8-1)^{9}=-1(1-8)^{9}\) \(=-1+{ }^{9} C_{1} 8-{ }^{9} C_{2} 8^{2}+\ldots+{ }^{9} C_{9} 8^{9}\) and \(\quad 9^{7}=(1+8)^{7}=1+{ }^{7} C_{1} 8+{ }^{7} C_{2} 8^{2}\) \(+{ }^{7} C_{3} 8^{3}+\ldots .+{ }^{7} C_{7} 8^{7}\)…
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