tolong dijawab ya kak..

29.
[tex]7 {x}^{2} y - 3x {y}^{2} - 7 {x}^{2}y + 5x {y}^{2} \\ = (7x^{2} y - 7 {x}^{2} y) + ( - 3x {y}^{2} + 5x {y}^{2} ) \\ = 0 + 2x {y}^{2} \\ = 2x {y}^{2} [/tex]
30.
4x + 5y - 8z + x - 2y - 3z
= (4x + x) + (5y - 2y) + (-8z - 3z)
= 5x + 3y - 11z

31.
[tex](3 {x}^{2} + 4x - 2) - (3 {x}^{2} - 6x - 2) \\ = 3 {x}^{2} + 4x - 2 - 3 {x}^{2} + 6x + 2 \\ = (3 {x}^{2} - 3 {x}^{2} ) + (4x + 6x) + ( - 2 + 2) \\ = 0 + 10x + 0 \\ = 10x[/tex]
32.

[tex] - 3a( - 4a + 5b) \\ = ( - 3a \times ( - 4a)) + ( - 3a \times 5b) \\ = 12 {a}^{2} - 15ab[/tex]
33.
4x - 5 = 11
4x = 11 + 5
4x = 16
x = 16 : 4
x = 4

34.
12 + 2x = 40
2x = 40 - 12
2x = 28
x = 28 : 2
x = 14