The C(x) equation is a parabola with a squared "x" and a positive leading term coefficient, meaning, is a vertical parabola and it opens upwards
the lowest point, or lowest cost value, it reaches, is the U-turn point, or vertex

so, the lowest cost is at
For this case we have the following equations:
y = 60x + 40
y = 50x + 80
Equaling both equations we have:
60x + 40 = 50x + 80
From here, we clear the value of x:
60x - 50x = 80 - 40
10x = 40
x = 40/10
x = 4 weeks
Substituting x = 4 in any of the equations we have:
y = 60 (4) + 40
y = 240 + 40
y = 280 $
Answer:
$ 280 4 weeks
In order to have average 80 score from 5 tests, student needs to have 400 points (80%*500=0.8*500=400)
So far he has 63+72+88+91= 314
400-314=86
He needs to get 86 points from the last test.
Since he is obviously getting better at tests, i think he'll manage :)
Answer:
y>6
Step-by-step explanation: