(C) Both (A) and (B)
Explanation
Step 1
a function where y is a function of x is given by:
[tex]y=f(x)[/tex]isolating y in (A)
[tex]\begin{gathered} 3y^4+2x-7=1 \\ 3y^4=1-2x+7 \\ 3y^4=-2x+8 \\ y^4=\frac{-2x+8}{3} \\ y=\pm\sqrt[4]{-2x+8} \\ \\ \end{gathered}[/tex]then, A is a function
Step 2
isolating y in (B)
[tex]\begin{gathered} x^2y+x=4y \\ +x=4y-x^2y \\ x=y(4-x^2) \\ y=\frac{x}{4-x^2} \end{gathered}[/tex]then, (B) is an equation that represents y as a function on x
I hope this helps you.
