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