passpadi

2001

Mathematics

67ca00ce0c643c71d77dee1f

Solve the equations m2 + n2 = 29 m + n = 7

A.

(2, 3) and ( 3, 5)

B.

(2, 5) and (5, 2)

C.

(5, 2) and ( 5, 3)

D.

(5, 3) and (3, 5)

Correct Answer: (2, 5) and (5, 2)

Explanation

m2 + n2 = 29 .......(1) m + n = 7 ............(2) From (2), m = 7 - n but m2 + n2 = 29, substituting; (7-n)2 + n2 = 29 49 - 14n + n2 + n2 = 29 => 2n2 -14n + 20 = 0 Thus n2 -7n + 10 = 0 Factorizing; (n-5)(n-2) = 0 n - 5 = 0, => n = 5 n - 2 = 0, => n = 2. When n = 5, m + n = 7, => m = 2, When n = 2, m + n = 7, => m = 5. Thus (m,n) = (5,2) and (2,5)

m2 + n2 = 29 .......(1) m + n = 7 ............(2) From (2), m = 7 - n but m2 + n2 = 29, substituting; (7-n)2 + n2 = 29 49 - 14n + n2 + n2 = 29 => 2n2 -14n + 20 = 0 Thus n2 -7n + 10 = 0 Factorizing; (n-5)(n-2) = 0 n - 5 = 0, => n = 5 n - 2 = 0, => n = 2. When n = 5, m + n = 7, => m = 2, When n = 2, m + n = 7, => m = 5. Thus (m,n) = (5,2) and (2,5)
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