Question

Which of the following are examples of quadratic functions?

• A. $f\left(x\right)=-2x^2+x-1$
• B. $f\left(x\right)=x^2+3x+2$
• C. $f\left(x\right)=x^3-1$
• D. None of these

Answer 1

Answer: (A), (B)

The correct options are
A $f\left(x\right)=-2x^2+x-1$
B $f\left(x\right)=x^2+3x+2$

A quadratic function is a polynomial function having one or more variables in which the highest degree term is of second degree

For example: $f\left(x\right)=x^2+2ax+4$

Here, highest degree is $2$ and therefore, it is a Quadratic equation.

Similarly,

In Option $\left(A\right)$ $f\left(x\right)=-2x^2+x-1$

Highest degree =$2$

In Option $\left(B\right)$ $f\left(x\right)=x^2+3x+2$

Highest degree =$2$

But in $\left(C\right)$ $f\left(x\right)=x^3-1$

Highest degree =$3$

Therefore it is not a Quadratic Equation

Hence Answer is $(A,B)$