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Question
Expand the following square, using suitable identities
(2x + 5)2
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Solution
(2x + 5)2
Comparing (2x + 5)2 with (a + b)2 we have a = 2x and b = 5
a = 2x and b = 5,
(a + b)2 = a2 + 2ab + b2
(2x + 5)2 = (2x)2 + 2(2x)(5) + 52
= 22x2 + 20x + 25
(2x + 5)2 = 4x2 + 20x + 25
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