Question 69

If x + y = 10 and $$x^2+ y^2$$ = 68, then find xy

Solution

Given : $$(x + y) = 10$$ and $$x^2 + y^2 = 68$$

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

=> $$(10)^2 = 68 + (2 \times xy)$$

=> $$2 xy = 100 - 68 = 32$$

=> $$xy = \frac{32}{2} = 16$$

=> Ans - (D)

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