Quantitative Aptitude – Algebra – Polynomials – If 9^(2x – 1) – 81^(x-1) = 1944

Quantitative Aptitude – Algebra – Polynomials

Question

If 9^(2x – 1) – 81^(x-1) = 1944, then x is

A) 3
B) 9/4
C) 4/9
D) 1/3

Answer

Option (B)

Solution

From CAT 2017 – Quantitative Aptitude – Algebra – Polynomials, we can see that,
9^(2x-1) – 9^(2x-2) = 1944
It can be written as 3^(4x)/9 – 3^(4x)/81 = 1944
8(3^(4x)/81) = 1944
x =9/4
Option (B)

Download CAT 2017 Question Paper with answers and detailed solutions in PDF

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