A(a-c+1)= a*a - a*c + a*1 = a^2-ac+a
5x(x+y^2-5)=5x*x+5x*y^2-5x*5= 5x^2+5xy^2-25x
-xy(3y^2+2x) = -xy*3y^2 + -xy*2x = -3xy^3 - 2x^2y
2^2xy(4x-3y+5xy) = 4xy(4x-3y+5xy) = 4xy*4x - 4xy*3y + 4xy*5xy = 16x^2y - 12xy^2 + 20x^2y^2
(x-a)(x+y) = x*x + x*y - a*x - a*y = x^2 +xy - ax - ay
(t+s)(b+k) = t*b + t*k + s*b + s*k = tb + tk + sb + sk
(a+2)(b-3) = a*b - a*3 +2*b - 3*2 = ab - 3a +2b - 6
(d-4)(t+5) = d*t + 5*d - 4*t - 4*5 = dt +5d - 4t - 20