Which equation represents y as a function of x

Question

A)x=10

b)sinx+y^4=6

c)y-6x^2=7x

d)3x=y^2

Answer 1

c) y = f(x) = 6x^2 -7x, an upward opening parabola, where you can never draw a vertical line through the parabola and cut it more than once. For every x value there is only one y value. If there are two y values for a given x value, it's not a function. all the others, a,b, and d have multiple y values for some x value. a) has an infinite number of y values for x =10