The profit that John got from the last 50 was $5000.
Consider the two functions as
<span>y1(x) =3x^2 - 5x,
y2(x) = 2x^2 - x - c
The higher the value of c, father apart the two equations will be.
They will touch when the difference, i.e. y1(x)-y2(x)=x^2-4*x+c has a discriminant of 0.
This happens when D=((-4)^2-4c)=0, or when c=4.
(a)
So when c=4, the two equations will barely touch, giving a single solution, or coincident roots.
(b)
when c is greater than 4, the two curves are farther apart, thus there will be no (real) solution.
(c)
when c<4, then the two curves will cross at more than one location, giving two distinct solutions.
It will be more obvious if you plot the two curves in a graphics calculator using c=3,4, and 5.
</span>
The standard conversion toolbox:
x=rcos(θ)
y=rsin(θ)
Here r=7csc(θ)
so
x=7csc(θ)*cos(θ)=7cos(θ)/sin(θ)=7cot(<span>θ)
y=7csc(</span>θ)*sin(θ)=7sin(θ)/sin(<span>θ) = 7
therefore the rectangular coordinates are (7cot(</span><span>θ), 7)</span>
I used similarities in triangles