[tex]a = x(5 - y)[/tex]
[tex]b = a(a + 3b)[/tex]
[tex]c = 12a(1 - b)[/tex]
[tex]d = - 12 {x}^{2} (x + 1)(2 {x}^{2} - 2x - 3)[/tex]
[tex]e = - 7 {x}^{2} (4 {x}^{2} - 10x - 1)[/tex]
[tex]f = (2 + x)(3 + y)[/tex]
[tex]g = (2x + 1)(x - 3)[/tex]
[tex]h = (5x + 2y)(x + 7)[/tex]
