Question

The time it takes a swimmer (in hours) to go a distance of 5 miles up and down a river is given by f(x)=4/x-1 hours and g(x)=3/x+1
hours respectively, where x is the speed of the swimmer (in miles per hour) in still water and (2≤ x ≤20). Find the expression for the total time it takes to go 5 miles up the river and come back to the same point.


a 7x-1/x^2-1
b x+7/x^2-1
c 12/x^2-1
d 7x+1/x^2-1

Answer 1

Very hard to understand what you have written.

Please evaluate:

8/4-1 =
9/(4-1) =

Let's see if we are understanding each other.

Answer 2

8/3 and 3

Answer 3

Okay, then we need to understand the Order of Operations a little better.

8/4-1 = (8/4) - 1 = 2 - 1 = 1

You must see that this is so.

Answer 4

I think a is correct.

Answer 5

no I think d

Answer 6

A is not correct as you have written it.

Do you see that 8/4-1 = 1 and if you want 8/3 the parentheses are NOT optional?

8/(4-1) = 8/3
8/4-1 = 1

Answer 7

I actually meant to write d.

Answer 8

D is also not correct as you have written it.

You should have:

f(x)=4/(x-1) hours
and
g(x)=3/(x+1) hours
The parentheses are NOT optional.

Distance = Rate * Time

Trip Up the River: \(5 = x\cdot\dfrac{4}{x-1}\)

Trip Down the River: \(5 = x\cdot\dfrac{3}{x+1}\)

Answer 9

So c

Answer 10

C is not correct as you have written it.

Why do you think so?