Question 62

If a + b = 11 and $$a^2 + b^2$$ = 61, then value of ab is

Solution

Given : $$(a + b) = 11$$ and $$a^2 + b^2 = 61$$

Using $$(a + b)^2 = a^2 + b^2 + 2ab$$

=> $$(11)^2 = 61 + (2 \times ab)$$

=> $$2 ab = 121 - 61 = 60$$

=> $$ab = \frac{60}{2} = 30$$

=> Ans - (D)

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