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How many pairs (m, n) of positive integers satisfy the equation m2 + 105 = n2?
Correct answer is '4'. Can you explain this answer?
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How many pairs (m, n) of positive integers satisfy the equation m2 + ...
N2- m2 = 105
(n-m) (n+m) = 1 *105, 3*35, 5*21, 7*15, 15*7, 21 *5, 35*3,105*1.
n – m=1, n+m=105==> n=53, m=52
n – m=3, n+m=35 ==> n=19, m=16
n – m=5, n+m=21 ==>n=13, m=8
n – m=7, n+m=15 ==> n=11, m=4
n – m=15, n+m=7 ==> n=11, m=-4
n – m=21, n+m=5 ==> n=13, m=-8
n – m=35, n+m=3 ==> n=19, m=-16
n – m=105, n+m=1 ==> n=53, m=-52
Since only positive integer values of m and n are required. There are 4 possible solutions.
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How many pairs (m, n) of positive integers satisfy the equation m2 + ...
Solution:

Given equation: m^2 - n^2 = 105

We can factorize the left-hand side of the equation as:

(m + n)(m - n) = 105

Since m and n are positive integers, we know that m + n > m - n. Therefore, we can write:

m + n > m - n ≥ 1

Thus, we have the following possibilities for the values of (m + n) and (m - n):

m + n = 105, m - n = 1
m + n = 35, m - n = 3
m + n = 21, m - n = 5
m + n = 15, m - n = 7

Solving each of these systems of equations, we get:

m = 53, n = 52
m = 19, n = 16
m = 13, n = 12
m = 11, n = 8

Therefore, there are 4 pairs of positive integers (m, n) that satisfy the given equation:

(53, 52), (19, 16), (13, 12), (11, 8)

Hence, the correct answer is 4.
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How many pairs (m, n) of positive integers satisfy the equation m2 + 105 = n2?Correct answer is '4'. Can you explain this answer?
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