What are the important points needed to graph g(x)= x^2-4x+4?

$x = - 2$
$g \left(x\right) = 4$
Both at their x/y intersects

Explanation:

Let's just make g(x)=y so it's easier.

$y = {x}^{2} - 4 x + 4$ Do the quadratic equation stuff you learned at school.
What multiplies to 4 and adds up to -4? It's -2. So $x = - 2$

And then to find y, plug 0 into x. Everything will multiply to 0 except the 4. So $y = 4$. graph{x^2-4x+4 [-3.096, 8.003, -0.255, 5.294]}