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Question
Expand.
(a + 2) (a − 1)
Sum
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Solution
Given:
(a + 2) (a – 1)
x = a
The first constant (a) = 2
The second constant (b) = –1
(x + a) (x + b) = x2 + (a + b)x + ab
Apply the identity
(a)2 + [2 + (–1)]a + (2 × –1)
Simplify the brackets
2 + (–1) = 1
2 × –1 = –2
Write the final terms
a2 + 1a – 2
(a + 2) (a – 1)
= a2 + a – 2
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