5 * ( a + 2 ) + ( a - 2 ) = 5a + 10 + a - 2 = 6a + 8
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2X * ( X + 1 ) - 4X * ( 2 - X ) = 2X² + 2X - 8X + 4X² = 6X² - 6X
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X * ( X² + X ) - ( X² + X + 1 ) = X³ + X² - X² - X - 1 = X³ - X - 1
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2Y² * ( 6Y - 1 ) + 3Y * ( Y - 4Y² ) = 12Y³ - 2Y² + 3Y² - 12Y³ = Y²