Resposta:
a)(x-7).(x-9)=0
[tex] {x}^{2} - 9x - 7x + 63 = 0 \\ {x}^{2} - 16x + 63 = 0[/tex]
b)4(x-5).(x+2)=0
[tex](4x - 20) \times (x + 2) = 0 \\ 4 {x}^{2} + 8x - 20x - 40 = 0 \\ 4 {x}^{2} - 12x - 40 = 0[/tex]
c)x(x+1).(x-4)=0
[tex]( {x}^{2} + x) \times (x - 4) = 0 \\ {x}^{3} - 4 {x}^{2} + {x}^{2} - 4x = 0 \\ {x}^{3} - 3 {x}^{2} - 4x = 0[/tex]
d)(x+6).(x-11).(x+8)=0
[tex]( {x}^{2} - 11x + 6x - 66) \times (x + 8) = 0 \\ ( {x}^{2} - 5x - 66) \times (x + 8) = 0 \\ {x}^{3} + 8 {x}^{2} - 5 {x}^{2} - 40x - 66x - 528 = 0 \\ {x}^{3} + 3 {x}^{2} - 106x - 528 = 0[/tex]
