range is the y values or ouputs
domain is inputs or x vvalues
we can use any x value
but at a certain y value, w can't go below that
find thatminimum
find the vertex
for
ax^2+bx+c
the x value of the vertex is
-b/2a
plug that in to the equaiton to get the y value
-b/2a=-(-6)/(2*2)=6/4=3/2
plug that in
2(3/2)^2-6(3/2)-9
2(9/4)-9-9
9/2-18
4.5-18
-13.5
domain=all real numbers
range=from -13.5 to positive infinity
