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Question
Expand the following:
(–x + 2y – 3z)2
Solution
(–x + 2y – 3z)2
= (–x)2 + (2y)2 + (–3z)2 + 2(–x)(2y) + 2(y)(–3z) + 2(–3z)(–x) ...[Using identity, (a + b + c)2 – a2 + b2 + c2 + 2ab + 2bc + 2ca]
= x2 + 4y2 + 9z2 – 4xy – 12yz + 6x
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