General Questions

Answer: Option D

Explanation:

x^m × xⁿ = x^{m + n}

9^x – 9^{x – 1} = 648

9^{x –} 1 (9 – 1) = 648

9^{x – 1} = (648/8) = 81

9^{x – 1} = 9²

x – 1 = 2

x = 2 + 1 = 3

x^x = 3³ = 27

Alternate solution:

Select the given options and substitute the value of x = 5, 6, 1.5 and 3 in the given expression.

Substituting value of x = 3,

9^x – 9^{x – 1} = ?

9³ – 9^{3 – 1} = 648

Value of x = 3

x^x = 3³ = 27