The distance between two cities is 220km. There are approximately 8km in 5 miles. What is the distance in miles?
1 answer:
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Answer:
The rate of current is 2.5 mph.
Step-by-step explanation:
The speed in the water when current is absent is 9 mph.
If the speed of the current is v mph then the upstream speed is (9 - v) mph and the downstream speed is (9 + v) mph.
Now, it takes 5 hours longer to travel 74 miles upstream than down stream, then we can write the equation as
⇒
⇒ 148v = 405 - 5v²
⇒ 5v² + 148v - 405 = 0
Applying Sridhar Acharya's formula we can write
(Neglecting the negative root)
⇒ mph (Rounded to the nearest 10th) (Answer)
The graph of the function 
is parabola with branches going down in the negative direction of y-axis.
The vertex of parabola has coordinates:
Then you can conclude that all x are possible, that means that the dimain is
and the maximum value of y is at the vertex, then the range is ![(-\infty,6]](https://tex.z-dn.net/?f=%28-%5Cinfty%2C6%5D)
.The function is increasing for x<-2 and decreasing for x>-2 (since vertex is the maximum point).
When x=0, y=2.
Hence,
<span>The domain is {x|x ≤ –2} - false.
</span>
<span>The range is {y|y ≤ 6} - true.
</span>
<span>The function is increasing over the interval (–∞ , –2) - true.
</span>
<span>The function is decreasing over the interval (−4, ∞) - false.
</span>
<span>The function has a positive y-intercept - true.</span>
The vertex of parabola has coordinates:
Then you can conclude that all x are possible, that means that the dimain is
When x=0, y=2.
Hence,
<span>The domain is {x|x ≤ –2} - false.
</span>
<span>The range is {y|y ≤ 6} - true.
</span>
<span>The function is increasing over the interval (–∞ , –2) - true.
</span>
<span>The function is decreasing over the interval (−4, ∞) - false.
</span>
<span>The function has a positive y-intercept - true.</span>