Which function is a quadratic function?

The function which is quadratic is:

We know that the general equation of a quadratic function is given by:

where a , b and c are real numbers.

1)

On solving we get:

Hence, the function is quadratic.

2)

It is not a quadratic equation since we have a term as :

and hence the equation will not match the general equation of the quadratic function.

3)

as it has a term of

Hence, it is a equation of a cubic function.

4)

On solving we get:

It does not has any term of

Hence, the equation is not a quadratic function it represent a linear function.

7

step-by-step explanation:

the answer would be 7