x - y - 3 = 0 This is a line...to graph it, pick some value for y, say 0.....then plugging this into the equation makes x = 3
So...we have one point on our graph, i.e., (3, 0) ....now pick another value for y, say 1......then, putting this into the equation forces x to be 4....and we have a second point → (4, 1)
And two points are all we need to draw a graph of a line.......so, plot the points and connect them......your graph should look like something like this........https://www.desmos.com/calculator/4inleaswpp
I possibly don't understand this, but I think you want to find the values where the differences in the height of the curves is more than 4 but less than 7....so we have....
[(1/2)x^2 + 7] - [(-1/4)x^2 + 3x] > 4 simplify
(3/4)x^2 - 3x + 7 > 4
(3/4)x^2 - 3x + 3 > 0 and this is > 0 everywhere except at x = 2 → ( -∞, 2) U (2, ∞)
See the graph, here....https://www.desmos.com/calculator/komufu5yah
And we also have
[(1/2)x^2 + 7] - [(-1/4)x^2 + 3x] < 7 simplify
(3/4)x^2 -3x + 7 < 7
(3/4)x^2 - 3x < 0 and the interval where this happens is (0, 4)
See the graph here.....https://www.desmos.com/calculator/eepspvllj9
Now......only the intersection of these intervals will satisfy this inequality.......these will be (0, 2) and (2, 4)
Note that when x = 2....the difference in the height of the curves is just 4......we need it larger than 4, though
See the graph here....https://www.desmos.com/calculator/hpb4r3uo1m
This one was a little tricky....I hope I haven't missed anything !!!