Point A: (-3, 11) Point B: (-3, 12) Point C: (-2, 17) Point D: (0, 11) Point E: 0, 12)
To find the x-intercepts by using the diamond method, you just use your standard form equation (y=x^2+8x-20). You multiply your first and last values and put that into the top section of your diamond. Then, you take the middle value and place that in the bottom. You then find your two values and then be able to solve your generic rectangle. You will find that they are x=-10 and x=2.
To fin the y-intercept you have to make y equal 0. Then you solve your equation for 0=x^2+8x-20. You should add 20 on both sides and that makes the equation 20+x^2=8x. If you set x=2, then you should get 20 on both sides which makes the y-intercept 2.
To find the vertex, you first have to take half of b and square it. Our standard for equation is y=x^2=8x-20. So did (x+4)^2 and got our new equation to be y= (x+4)^2-36. To get the ordered pair, you just take the opposite of your "h" and make it your first number in your ordered pair. In this case, it's -4. To get the second number, you just take your "c" value. Our ordered pair is (-4,36).