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Question
Using (x + a) (x + b) = x2 + (a + b) x + ab, find 5.1 × 5.2
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Solution
5.1 × 5.2 = (5 + 0.1) (5 + 0.2)
= (5)2 + (0.1 + 0.2) (5) + (0.1) (0.2)
= 25 + 1.5 + 0.02 = 26.52
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