Question
If (a +
b) = 13 and (a2 + b2) = 85, then find the value of (a ×
b).
Solution
(a + b) = 13 Squaring on both sides, we get, a2 + b2 + 2ab = 169 Or, 85 + 2ab = 169 Or, 2ab = 169 – 85 = 84 Or, ab = 84/2 = 42
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