- 5x² + 20x - 20 = - 5 *( x² - 4x + 4 ) = - 5 * ( x - 2 )*( x - 2 )
( или - 5 * ( x - 2 )² )
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4c² - 64d⁴ = 4*( c² - 16d⁴ ) = 4*( c - 4d² )*( c + 4d² )
( или 4*( √ c - 2d )*( √ c + 2d )*( c + 4d² ) )