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Question
Using the identity (x + a)(x + b) = x2 + x(a + b) + ab, find the following product
(x + 3)(x + 7)
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Solution
(x + 3)(x + 7)
Let a = 3, b = 7
(x + 3)(x + 7) is of the form x2 + x(a + b) + ab
(x + 3)(x + 7) = x2 + x(3 + 7) + (3 × 7)
= x2 + 10x + 21
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