Question

For what value of $k$ will the quadratic equation: ${kx}^2+4x+1=0$ have real and equal roots ?

• A. 2
• B. 3
• C. 4
• D. 1

Answer 1

Answer: (C)

4

The given quadratic equation is :
${kx}^2+4x+1=0$
Here, $a=k,b=4,c=1$
Now, $D=b^2-4ac={\left(4\right)}^2-4\times k\times 1=16-4k$
We know that a quadratic equation has real and equal roots
If $D=0$
$\Rightarrow 16-4k=0$
$\Rightarrow -4k=-19$
$\therefore k=\frac{-16}{-4}=4$