53x-1 ÷ 25 = 125 then x = ……………… A) – 2 B) 2 C) 4

1.	53x-1 ÷ 25 = 125 then x = ……………… A) – 2 B) 2 C) 4 D) 3
Answer» Correct option is (B) 2 \(5^{3x-1}\div25\) = 125 \(\Rightarrow\frac{5^{3x-1}}{25}=125\) \(\Rightarrow\) \(5^{3x-1}=5^2\times5^3=5^{2+3}=5^5\) \(\Rightarrow\) \(3x-1=5\) \(\Rightarrow\) 3x = 5+1 = 6 \(\Rightarrow x=\frac63=2\) Correct option is B) 2 B) 2 5^3x-1 = 5^5 3x-1 = 5 3x = 6 x = 2

53x-1 ÷ 25 = 125 then x = ……………… A) – 2 B) 2 C) 4 D) 3

Answer»

Correct option is (B) 2

\(5^{3x-1}\div25\) = 125

\(\Rightarrow\frac{5^{3x-1}}{25}=125\)

\(\Rightarrow\) \(5^{3x-1}=5^2\times5^3=5^{2+3}=5^5\)

\(\Rightarrow\) \(3x-1=5\)

\(\Rightarrow\) 3x = 5+1 = 6

\(\Rightarrow x=\frac63=2\)

Correct option is B) 2

B) 2

5^3x-1 = 5^5

3x-1 = 5

3x = 6

x = 2