Question 42

If a + b = - 8 and $$a^{2} + b^{2} = 34$$, then value of ab is

Solution

Given : $$(a + b) = -8$$ and $$a^2 + b^2 = 34$$

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

=> $$(-8)^2 = 34 + (2 \times ab)$$

=> $$2 ab = 64 - 34 = 30$$

=> $$ab = \frac{30}{2} = 15$$

=> Ans - (D)

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