Step-by-step explanation:
[tex] 3{x}^{4} + 11 {x}^{3} - 4 {x}^{2} = 0 \\ factor \: {x}^{2} out \: of \: 3 {x}^{4} + 11 {x}^{3} - 4 {x}^{2} \\ \\ {x}^{2} ( 3{x}^{2} + 11x - 4) = 0 \\ {x}^{2} (3x - 1)(x + 4) = 0 \\ {x}^{2} = 0 \\ 3x - 1 = 0 \\ x + 4 = 0 \\ [/tex]
[tex]x = 0 \\ x = \frac{1}{3} \\ x = - 4 \\ [/tex]
The final solution is
x=(0 , 1/3 , -4 )