What number must be added to the polynomial to complete the square? x^2 + 7x

It could be: (x + 7/2)^2 = x^2 + 7x + 49/4
So you should add it by 49/4.

Where the white dots are is where your points should be plotted.a translation is simply just moving something from one place to another. in this case, you would move each plot point of the original shape 2 units up, and 5 units to the left.