Question 155373
5x^2y^6z^4 - 15x^4y^5z^3 + 20x^3y^5z^2
5x^2y^5z^2(yz^2-3x^2z+4x)
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12xy + 20yz - 40wy
4y(3x+5z-10w)
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16x^2 - 49
(4x^2+7)(4x^2-7)