Answer
See below
Work Step by Step
Given: $-3x^4+4x^3+8x^2+4x-11=13$
Separate the left side and the right side of the equation:
$y=13\\y=-3x^4+4x^3+8x^2+4x-11$
The red graph is the graph of $y=13$. The blue graph is the graph of $y=-3x^4+4x^3+8x^2+4x-11$