Question

If $(a+b)x^5+3(b+2)x^3+3x^2+17$ is a quadratic polynomial, then the value of $a,b$ are:

• A. $a=2,b=-2$
• B. $a=2,b=2$
• C. $a=-2,b=-2$
• D. $a=-2,b=2$

Answer 1

The correct option is A $a=2,b=-2$

Given that $(a+b)x^5+3(b+2)x^3+3x^2+17$ is a quadratic polynomial.
For this to be a quadratic polynomial, the highest power of the variable must be $2$.
$\Rightarrow$ the coefficients of the $x^5$ and $x^3$ terms must be zero.
$b+2=0\Rightarrow b=-2$
And $a+b=0$
$\Rightarrow a-2=0\Rightarrow a=2$