If \( \Large x-y=1\ and\ x^{2}+y^{2}=41, \), then value of x+y will be


A) 9 or -9

B) 1 or 9

C) -1 or 9

D) -1 or -9

Correct Answer:
A) 9 or -9

Description for Correct answer:
Given \( \Large x-y = 1\ or\ x = 1 + y \)

and \( \Large x^{2}+y^{2} = 41 \)

Substituting value of x from equation (i) in equation (ii), we get

\( \Large \left(1+y\right)^{2}+y^{2}=41 \)

=> \( \Large 2y^{2}+2y +1 = 41\)

=> \( \Large 2y^{2}+2y-40 = 0 \)

=> \( \Large \left(y+5\right) \left(y-4\right) = 0 \)

Therefore, y = -5 or 4

From equation (i)

x = -4 or 5

Therefore, x+y = -9 or 9

Part of solved Rational expression questions and answers : >> Elementary Mathematics >> Rational expression








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