Question

The quadratic Formula uses the $a,b$, and $c$ from $a{x}^2+bx+c$, where $a,b$, and $c$ are just numbers; they are the "numerical coefficients" of the quadratic equation they've given you to solve. Now, solve the following quadratic polynomials and find out the value of $k$.
If the sum of zeroes of the quadratic polynomials $4x^2+kx+9$ is -2 , find the value of $k$.

• A. 6
• B. 7
• C. 8
• D. 9

Answer 1

Answer: (C)

Given: $4x^2+kx+9$
Here, $a=4,b=k,c=9$
Sum of zeroes, $(\alpha +\beta )=\frac{-b}{a}=-2$
$\Rightarrow \frac{-b}{a}=-2$
$\Rightarrow \frac{-k}{4}=-2\Rightarrow k=8$