Answer:
x=-8, x=1/4, x=5.
Step-by-step explanation:
The degree is 3, so there must be 3 roots.
factor: x^2(4x-1)+3x(4x-1)-40(4x-1)=0
=(4x-1)(x^2+8x-5x-40)=0
=(4x-1)(x+8)(x-5)=0
x=1/4, -8, 5
