f)
[tex]xy {z}^{2} - 4y {z}^{2} + 4xy {z}^{2} + 2yz = 5xy {z}^{2} - 4y {z}^{2} + 2yz[/tex]
g)
[tex] - 2a + b + 4b - 7a + 9 = - 9a + 5b + 9[/tex]
h)
[tex]4 {xy}^{2} + 6 { x }^{2} y - 2{y}^{2} x = 4 {xy}^{2} + 6 {x}^{2} y - 2x {y}^{2} = 2 {xy}^{2} + 6 {x}^{2} y[/tex]
i)
[tex]3 {k}^{2} - 2k + {k}^{2} - 2 {k}^{2} - k + 9 {k}^{3} = 2 {k}^{2} - 3k + 9 {k}^{3} [/tex]
j)
[tex]5 {a}^{2} + 2ab - {a}^{2} b + ab - 3 {a}^{2} = 2 {a}^{2} + 3ab - {a}^{2} b[/tex]
