Question

Which of the following is a cubic polynomial ?

• A. $x^3+3x^2-4x+3$
• B. $x^2+4x-7$
• C. $3x^2+4$
• D. $3(x^2+x+1)$

Answer 1

Answer: (A)

$x^3+3x^2-4x+3$

A cubic polynomial is a polynomial of degree $3$, or in simpler words highest power of $x$ is $3$.

It is of the form $f\left(x\right)=a{x}^3+b{x}^2+cx+d$ where $a,b,c,d$ belongs to real numbers.

We can see that in option A, $x$ has the highest power $3$ and $a=1,b=3,c=-4$ and $d=3$.

Rest of the options $B,C,D$ have the highest power as $2$.

Hence, they are quadratic polynomials.

Correct option is $A$