Which equation does not show y as a function of x

a.) y = x2 + 7x + 2
b.) y = 3x + 7
c.) y = | 4x |
d.) x = y2 + 3

d

for x to be a function it should satistfy two (both) facts;
1) each x term should have one and only one respective y value!
2)each y value should have a corresponding x value, null values not accepted

consider D) x = y2 + 3
subject y
y = +/- sqrt (x-3)
let x =7
y= +/-2
one x value hs TWO corresponding y values
this goes against fact (1)
so d) is the answer
consider the others youll note that they satisfy both facts:)

hope that was helpful

d.) shows x as a function of y

d) because its not written wrt y, i.e equation starts with x

All do.