We know that the amounts earned by Dawn, Doug and Dale are from the list of numbers: $9.35, $8.52 and $8.25
We also know that Dale and Doug earned close to $9.00
And that Dawn earned $1.10 less than Dale
Let the amount earned by Dale be x
⇒ Amount earned by Dawn is x - 1.1
If we notice the list of numbers, we see that $9.35 and $8.25 differ by $1.1
Hence, Dale earned $9.35 and Dawn earned $8.25
We are now left with $8.52, which should be the amount earned by Doug. This is correct, since we also know that Doug earned close to $9.
Hence, the amounts earned are:
Dale: $9.35
Doug: $8.52
Dawn: $8.25
3 x^3 y^2
_______
8 ( y/x-3/2)
This response is based upon your having had some background in calculus. "dx" is not introduced before that.
Take a look at the sample function y = f(x) = x^2 + 9. Here x is the independent variable; the dependent variable y changes with x.
Now, for a big jump: we consider finding the area under a curve (graph) between x = a and x = b. We subdivide that interval [a,b] into n vertical slices of area. Each of those slices has its own area: f(x)*dx, where dx represents the width of such subarea. f(x)*dx is the actual subarea. To find the total area under the curve f(x) between x= a and x = b, we add up all of these individual subareas between x = a and x = b. Note that the subinterval width is
b-a
dx = ---------- , and that dx becomes smaller and smaller as the number of
n subintervals increases.
Once again, this all makes sense only if you've begun calculus (particularly integral calculus). Do not try to relate it to earlier math courses.
