For what value of $k$ does $kx^2 - 12x + 4 = 0$ have two equal roots?

Explanation

1. 01

   Equal roots need discriminant $= 0$: $(-12)^2 - 4 \times k \times 4 = 0$.

2. 02

   $144 - 16k = 0$, so $k = 9$.

3. 03

   Check: $9x^2 - 12x + 4 = (3x - 2)^2$.