Question

Find the value of k ,so that they have two equal roots : 2x2 + kx + 3= 0

Answer 1

$\boxed{\text{Quadratic Formula : }x=\frac{-b\pm\sqrt{b^2-4ac} }{2a} }$

$\boxed{\text{If square root is zero, two solutions are same which are }x=\frac{-b}{2a} }$

Now, it is required that $b^2-4ac=0$. For your information, this value is called quadratic discriminant, and often called D.

→ $D=k^2-24$

It is required that the value is 0.

→ $k^2=24$ → $k=\pm\sqrt{24}$

Therefore, two values of k are square roots of 24.