Question

In which direction does the graph of the function shown below open?


`f(x) = 2x^2+5x-4`

A. Down
B. Left
C. Right
D. Up

Answer 1

D. Up

Explanation:

When a parabola has the form
`y=ax^2+bx+c` , It is vertical (opens up or down).

Because the variable "x" is squared.

If "a" is positive, then the parabola opens up, but if it is negative, then the parabola opens down.

In this case you have the quadratic function:

`f(x) = 2x^2+5x-4`

Which can be rewritten as:

`y = 2x^2+5x-4`

Therefore, it is vertical, because it has the form:
`y=ax^2+bx+c`

You can observe that the value of "a" is:

`a=2`

Then, since "a" is positive, the parabola opens up.