= (a^2 + ab) + (ac + bc) = a(a + b) + c(a + b) = (a + b)*(a + c)
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= (ab + 2b) - (2a+ 4) = b(a +2) - 2(a +2) = (b-2)*(a + 2)
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= (x^2 + ax) + (xy + ay) = x(x +a) + y(x + a) = (x+y)*(x+a)
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= (am-an) + (m - n) = a(m-n) + 1(m-n) = (a + 1)*(m -n)
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= ?
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= (ab - a^2) - (2b - 2a) =a(b - a) - 2(b - a) = (a-b)*(b - a)