2 x + 6*x - 7
x^2 + 6*x - 7
2 -7 + x + 6*x
-7 + x^2 + 6*x
(x + 7)*(x - 1)
(-1 + x)*(7 + x)
-7.0 + x^2 + 6.0*x
-7 + x*(6 + x)