Correct Answer: Option C

Explanation

x + y = 5.......(i)

x2 - 2y2 = 1.......(ii)

x = 5 - y.........(iii)

Subst. for x in eqn.(ii) = (5 - y)2 - 2y2 = 1

25- 10y + y2 - 2y2 = 1

25 - 1 = y2 + 10y

y2 + 10y2 - 24 = 0

(y + 12)(y - 2) = 0

Then Either y + 12 = 0 or y - 2 = 0

= (-12, +2)

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