**If x**^{2} + y^{2} = 9 and xy = 8, then x + y is equal to

^{2}+ y

^{2}= 9 and xy = 8, then x + y is equal to

(a) 25

(b) 5

(c) -5

(d) ± 5

**Answer : (d) ± 5**

**Hint:**

x^{2} + y^{2} = 9, xy = 8

Or, x^{2} + y^{2} + 2xy = 9 + 2xy

Or, (x^{2} + y)^{2} = 9 + 2 × 8

Or, x + y = √25 = ± 5

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