Length of a circle=2πr
r=40 m
Length of the circular track=2*π*40m=80π m.
The athelete jogs each day 10 laps
1 lap-------------------80π m
10 laps------------- x
x=(10 laps * 80π m) / 1 lap=800π m
Calculate how far he jog eache week (5 days).
1 day------------------800π m
5 days---------------- x
x=(5 days*800π m)/1day=4000π m=4000m * 3.141592...≈12566,37 m
solution: 12566 m
The denominator of the first term is a difference of squares, such that
4<em>a</em> ² - <em>b</em> ² = (2<em>a</em>)² - <em>b</em> ² = (2<em>a</em> - <em>b</em>) (2<em>a</em> + <em>b</em>)
So you can write the fractions as
(4<em>a</em> ² + <em>b</em> ²)/((2<em>a</em> - <em>b</em>) (2<em>a</em> + <em>b</em>)) - (2<em>a</em> - <em>b</em>)/(2<em>a</em> + <em>b</em>)
Multiply through the second fraction by 2<em>a</em> - <em>b</em> to get a common denominator:
(4<em>a</em> ² + <em>b</em> ²)/((2<em>a</em> - <em>b</em>) (2<em>a</em> + <em>b</em>)) - (2<em>a</em> - <em>b</em>)²/((2<em>a</em> + <em>b</em>) (2<em>a</em> - <em>b</em>))
((4<em>a</em> ² + <em>b</em> ²) - (2<em>a</em> - <em>b</em>)²) / ((2<em>a</em> - <em>b</em>) (2<em>a</em> + <em>b</em>))
Expand the numerator:
(4<em>a</em> ² + <em>b</em> ²) - (2<em>a</em> - <em>b</em>)²
(4<em>a</em> ² + <em>b</em> ²) - (4<em>a</em> ² - 4<em>ab</em> + <em>b</em> ²)
4<em>ab</em>
<em />
So the original expression reduces to
4<em>ab</em> / ((2<em>a</em> - <em>b</em>) (2<em>a</em> + <em>b</em>))
or
4<em>ab</em> / (4<em>a</em> ² - <em>b</em> ²)
upon condensing the denominator again.
Answer:
If you look over the steps you can see that until 4x + x + 3 = 18, evertything is dandy. But the step after that 4x + x =21 seems a bit fishy.
Think about it they subtract 3 from both sides so the first side is correct
4x + x, but they added 3 to the other side:
not
4x+x = 21
Then we solve for 4x + x = 15
To solve for y we use :
y = x+3
y = 3+3 = 6
so (3,6) is the right answer
