72n+1 ÷ 49 – 73 then n = ……………… A) – 2 B) 2 C) 3

1.	72n+1 ÷ 49 – 73 then n = ……………… A) – 2 B) 2 C) 3 D) -3
Answer» Correct option is (B) 2 \(7^{2n+1}\div49=\frac{7^{2n+1}}{49}=\frac{7^{2n+1}}{7^2}\) \(=7^{2n+1-2}=7^{2n-1}\) \(\because\) \(7^{2n+1}\div49=7^3\) \(\therefore\) \(7^{2n-1}=7^3\) \(\Rightarrow\) 2n - 1 = 3 \(\Rightarrow\) \(n=\frac{3+1}2=\frac42=2\) Correct option is B) 2

72n+1 ÷ 49 – 73 then n = ……………… A) – 2 B) 2 C) 3 D) -3

Answer»

Correct option is (B) 2

\(7^{2n+1}\div49=\frac{7^{2n+1}}{49}=\frac{7^{2n+1}}{7^2}\) \(=7^{2n+1-2}=7^{2n-1}\)

\(\because\) \(7^{2n+1}\div49=7^3\)

\(\therefore\) \(7^{2n-1}=7^3\)

\(\Rightarrow\) 2n - 1 = 3

\(\Rightarrow\) \(n=\frac{3+1}2=\frac42=2\)

Correct option is B) 2