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Question
Expand : (3x - 5y - 2z) (3x - 5y + 2z)
Sum
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Solution
(3x - 5y - 2z) (3x - 5y + 2z)
= {(3x - 5y) - (2z)} {(3x - 5y) + (2z)}
= (3x - 5y)2 - (2z)2{since(a + b) (a - b) = a2 - b2}
= 9x2 + 25y2 - 2 × 3x × 5y - 4z2
= 9x2 + 25y2- 30xy - 4z2
= 9x2 +25y2 - 4z2 - 30xy
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