Solutions
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Question
If (2^x) (2^y) = 8 and (9^x)(3^y) = 81, then (x,y) equals:
Option A:
(1,2)
Option B:
(2,1)
Option C:
(1,1)
Option D:
(2,2)
Option E:
(1,3)
Difficulty Level
EasySolution
Option A is the correct answer.
Option Analysis
Given (2^x) (2^y) = 8,
2^(x+y) = 2^3
x+y = 3 (from Equation 1)
(9^x)(3^y) = 81,
3^(2x) * (3^y) = 3^4
3^(2x+y) = 3^4
So 2x+y = 4 (from Equation 2)
Solving, Equation 2 – Equation 1
We get, x = 1 and y =2