If 2n = 128, then (2n–1) (5n-2) = ?

If 2ⁿ = 128, then (2ⁿ^–1) (5^n-2) = ?

A 2 × 10⁵

B 5 × 10⁵

C 2 × 10⁶

D 2 × 5⁶

Solution

Correct Answer: Option A

দেওয়া আছে,

2ⁿ = 128

⇒ 2ⁿ = 27

∴ n=7

তাহলে,

(2ⁿ^–1) (5^n-2)

= (2⁷^–1) (5^7-2)
= (2⁶) (5⁵)
= 2 × 2⁵ × 5⁵
= 2 × 10⁵