Question

Which equation does not represent a function? Why? A) y = x2; There are two outputs for each input. B) y2 = 4x; There are two outputs for each input. C) y = x; The output value is the same as the input value. D) y = −x; The output value is the opposite of the input value.

Answer 1

B

Explanation:

Answer 2

B) y² = 4x; There are two outputs for each input

Explanation:

For an equation to be called a function, the input values for x must only result in a single output for y.

Based on this definition if a function, the functions y = x², y = -x and y = x are all functions because for any value of x imputed in them, we can only get one equivalent value of y.

The only exception is the function y²= 4x

For this function, for any value of x, there will be more than one output for y. Take x = 1 for example

y² = 4(1)

y² = 4

y = ±√4

y = ±2

This shows that y = 2 and -2

Also if x = 4

y² = 4(4)

y² = 16

y = ±√16

y = ±4

y = 4 and -4

No matter the value of x imputed, the output value y will always be two (a positive and a negative value)

Hence, option B is correct.