Quantitative Aptitude – Algebra – Equation


Slot – 2 – Quantitative Aptitude – Algebra – Equation – How many pairs (m, n) of positive

Q. How many pairs (m, n) of positive integer satisfy the equation m^2+105=n^2 ?

Answer: 4

Solution: Given m^2 + 105 = n^2
n^2 – m^2 = 105
(n-m) * (n+m) = 105
105 can be written as 105*1 = 21*5 = 15*7 = 35*3
So, only 4 cases possible to get values of n, m as positive. Thus number of solution = 4

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