Question 44

If a + b = 10 and $$a^2 + b^2$$ = 58, then find ab

Solution

Given : $$(a + b) = 10$$ and $$a^2 + b^2 = 58$$

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

=> $$(10)^2 = 58 + (2 \times ab)$$

=> $$2 ab = 100 - 58 = 42$$

=> $$ab = \frac{42}{2} = 21$$

=> Ans - (A)

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