Which of the following is a parabola?

Question

a. y^2 +x^2 + 2 x +3 = 0

b. x - 2x + 3 = 0

c. x^2 + y^2- 2x + 3 = 0

d. x^2 + y - 2x +3 = 0

Answer 1

The parabola in standard form is       y=ax²+bx+c

 

where a , b , and c are constants.

 

 

By analysis, we see that choice (d) is a reasonable choice.  This is because the exponent of y is 1.  Now we solve for y from the equation represented by choice (d).

 

y = -x² + 2x - 3

 

 

Choices (a) and (c) represent square-root functions.  Choice (b) represents a vertical line at x=3.