(c - 4)*(c + 1) - (c - 2)*2
(c - 4)*(c + 1) - (c - 2)*2 при c = -1
((-1) - 4)*((-1) + 1) - ((-1) - 2)*2
(-1 - 4)*(-1 + 1) - (-1 - 2)*2
6
4 - 2*c + (1 + c)*(-4 + c)
4.0 - 2.0*c + (1.0 + c)*(-4.0 + c)
c*(-5 + c)
2 c - 5*c