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Jesse is traveling up and down a stream in a kayak. He can paddle the kayak at an average rate of 5 miles/hour, and the round-trip is a total distance of 16 miles. When [tex]\( c \)[/tex] is the speed of the current, this expression can be used to find the difference in the time it takes Jesse to travel upstream (against the current) and downstream (with the current):

[tex]\[ \frac{8}{5-c} - \frac{8}{5+c} \][/tex]

Find the difference in simplest form.


Sagot :

Sure, let's break down the given mathematical expression step by step and simplify it.

We start with the given expression:
[tex]\[ \frac{8}{5 - c} - \frac{8}{5 + c} \][/tex]

To simplify this, we should first get a common denominator for the two fractions. The denominators in this case are [tex]\(5 - c\)[/tex] and [tex]\(5 + c\)[/tex]. The common denominator would be the product of these two denominators, which is [tex]\((5 - c)(5 + c)\)[/tex].

Rewriting each fraction with the common denominator, we get:
[tex]\[ \frac{8(5 + c)}{(5 - c)(5 + c)} - \frac{8(5 - c)}{(5 - c)(5 + c)} \][/tex]

Now, we can combine these two fractions into a single fraction:
[tex]\[ \frac{8(5 + c) - 8(5 - c)}{(5 - c)(5 + c)} \][/tex]

Next, we simplify the numerator:
[tex]\[ 8(5 + c) - 8(5 - c) = 8 \cdot 5 + 8 \cdot c - 8 \cdot 5 + 8 \cdot c = 8c + 8c = 16c \][/tex]

So, the simplified form of the numerator is [tex]\(16c\)[/tex].

The denominator, [tex]\((5 - c)(5 + c)\)[/tex], is a difference of squares and can be simplified to:
[tex]\[ 5^2 - c^2 = 25 - c^2 \][/tex]

Putting it all together, we can now write the simplified fraction as:
[tex]\[ \frac{16c}{25 - c^2} \][/tex]

Therefore, the simplified expression for the difference in time it takes Jesse to travel upstream and downstream is:
[tex]\[ \boxed{-\frac{16c}{c^2 - 25}} \][/tex]