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3 years ago

Math question. Please help

Mathematics

1 answer:

Leya [2.2K]3 years ago

7 0

Time = distance/speed
total time = time for part 1 + time for part 2 + time for part 3
.. t = 5/r +6/(0.6r) +1/(r+1)
.. = (1/r)*(5 +6/0.6) +1/(r +1)
.. = 15/r +1/(r +1)
Add these fractions in the usual way.
.. = (15(r +1) +r)/(r(r +1))
.. t = (16r +15)/(r(r +1)) . . . . . . . . . your expression for t

For r=3, this is
.. t = (16*3 +15)/(3*(3 +1))
.. = 63/12
.. = 5 3/12
.. = 5 15/60
The trip takes 5 hours and 15 minutes

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Answer:

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Step-by-step explanation:

(a)

Given:

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Then, from the figure,

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(b)

Given:

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For maximum area, derivative of area with respect to $x$ must be 0.

So, $\frac{dA}{dx}=0\\\frac{d}{dx}(160x-2x^{2})=0\\160-4x=0\\4x=160\\x=\frac{160}{4}=40\textrm{ m}$

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(c)

Given:

$A(x)=160x-2x^{2}$

Maximum area occurs at $x=40$ . Plug in 40 for $x$ in $A(x)$ expression. This gives,

Maximum area is,

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