Trying to find the right answer to this..

LHS = (3x + 7) - 84x = (3x) 2 +2(3x)(7) + (7) 2 - 84x = 9x 2 + 42x + 49 - 84x = 9x 2 + (42 - 84) x + 49 = 9x 2 -42x + 49 RHS = (3x - 7) 2 = (3x) 2 -2(3x)(7) + (7) 2 = 9x 2 - 42x + 49 Since, LHS = RHS ∴ (3x + 7) 2 -84x = (3x -7) 2

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Algebraic Expressions and Identities

Short Answer Type

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(3x + 7)²-84x = (3x -7)²

LHS = (3x + 7) - 84x
       = (3x)²+2(3x)(7) + (7)² - 84x
       = 9x² + 42x + 49 - 84x
       = 9x²+ (42 - 84) x + 49
       = 9x²-42x + 49

RHS = (3x - 7)²

      = (3x)²-2(3x)(7) + (7)²

     = 9x² - 42x + 49

Since, LHS = RHS

∴ (3x + 7)²-84x = (3x -7)²

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