Question 906170
{{{x^2-4x}}} is not a square and what you want is a square.  You have so far, something which can
be matched to a rectangle area, {{{x(x-4)}}}.  If you  ADD and SUBTRACT  {{{(-4/2)^2=4}}}, you can complete the square
and part of the resulting expression can be factored:


{{{f(x)=x^2-4x+4-4}}}
{{{f(x)=(x^2-4x+4)-4}}}
{{{highlight(f(x)=(x-2)^2-4)}}}----standard form.


The vertex is (2,-4), and because coefficient on the squared expression is POSITIVE 1,
this vertex is a minimum.


If you want to know the x-intercepts, solve for x in {{{highlight_green((x-2)^2-4=0)}}}, a very simple
and easy process.


Finding y-intercept just means let x=0 and evaluate y.