Quantitative Aptitude – Algebra – Quadratic Equation


Slot – 2 – Quantitative Aptitude – Algebra – Quadratic Equation – If 5^x – 3^y = 13438

Q. If 5^x – 3^y = 13438 and 5^(x-1) + 3^(y+1) = 9686, then x+y equals?

Answer: 13

Solution: Given,
5^x – 3^y = 13438—–(1)
5^(x-1) + 3^(y+1) = 9686—-(2)
From equation 2, we get
5^x /5 + 3. 3^y = 9686
Multiplying equation 1 by 3 and adding, we get
5^x = 15625
So, x = 6
Putting x in equation 1, we get
3^y = 2187
Y = 7
So, x+y = 13

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