equal roots of an equation

In the quadratic equation $ax^2+bx+c=0$ , the roots are equal if $b^2-4ac$ is zero. From the given, we have

$a=1,b=2(k+2)=2k+4,c=9k$

Substitute:

$(2k+4)^2-4(1)(9k)=0$

$4k^2+16k+16-36k=0$

$4k^2-20k+16=0$

$k^2-5k+4=0$

$(k-4)(k-1)=0$

$k=4$ and $k=1$

The desired answer is $k=4$ .