Question

How can I determine a equation from a graph? How can I determine how to graph y = x^2 + x - 2? Or y = x^2 - 4x + 4? Am I supposed to use the slope method (rise and run)?

Answer 1

I bet you have the zeroes from the graph. Look to see when the graph crosses the x axis, say at a and b.
then (x-a)(x=b)=0 mulitpy it out and you have it.

graphing y=x^2 -x-2=(x-2)(x+1)
it is zero (crosses x axis) at x=2, and x=-1. The max will be half way between those, or at x=.5
What is the max? Put in x=.5, calculate y. Graph those points

Answer 2

I tried the same method that you did to graph the equation y =x^2 -4x + 4 and my x-intercepts are both -2 (the y-intercept is y= 4). However, according to wolfram, the x-intercept should be 2. Who is correct: me or the website?

Answer 3

You did not factor correctly.
x^2-4x+4 = (x-2)(x-2)

If that's what you got, then you clearly don't understand what it means.

x-2 = 0 when x=2, not -2.