Question 64

If x + y = 13 and $$x^2 + y^2$$ = 89, then find xy is

Solution

Given : $$(x + y) = 13$$ and $$x^2 + y^2 = 89$$

Using $$(x + y)^2 = x^2 + y^2 + 2xy$$

=> $$(13)^2 = 89 + (2 \times xy)$$

=> $$2 xy = 169 - 89 = 80$$

=> $$xy = \frac{80}{2} = 40$$

=> Ans - (D)

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