Question

For each of the following equations, determine whether y is a function of x.

x= -7y^2
b. x = 1/4y
c. y^2 = 4x +9
d. y= 5x +8

Answer 1

9514 1404 393

Answer:

a) not a function

b) is a function

c) not a function

d) is a function

Explanation:

If the graph passes the "vertical line test," then the relation is a function.

Choices B and D are linear equations. Their graph is a straight line, so each x-value corresponds to exactly one y-value. (Every non-vertical line passes the vertical line test.)

Choices A and C are equations of parabolas that open horizontally. It is easy to draw a vertical line that intersects the graph twice, so these relations fail the vertical line test.

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B, D -- functions

A, C -- not functions