Consider the following position function. Find (a) the velocity and the speed of the object and (b) the acceleration of the object. r(t) = (9,t^3, e^-t), for t greater than or equal to 0

v = 3t^2, -e^-t ;

Speed = √ 9t^4 + (-e^-t)^2 ;

a(t) = 6t, e^-t

Step-by-step explanation:

Given the position function at time 't' for t greater than or equal to 0:

r(t) = (9,t^3, e^-t)

The Velocity of 'v' is the first derivative of r with respect to 't' :

d/dt(9) = 0

d/dt(t^3) = 3t^3-1 = 3t^2

y = (e^-t) =

Using chain rule :

Let u = -t

y = e^u ; dy/du = e^u

du/dt = -1 ;

Therefore dy/dt = dy/du * du/dt

dy/dt = -1 * e^u ; -e^u ; u = -t

dy/dt = -e^-t

Therefore,

v = 3t^2, -e^-t

The magnitude of velocity 'v ' = speed

Speed = √v1^2 + v2^2

Speed = √(3t^2)^2 + (-e^-t)^2

Speed = √ 9t^4 + (-e^-t)^2

Acceleration(a) = derivative of velocity

d/dt(3t^2) = 6t

d/dt (-e^-t) :

Using chain rule :

dy/dt = -e^-t

Let u = -t ; du/dt = -1

-e^u ; dy/du = -e^u

Therefore, dy/dt = -1 * -e^u

u = -t

dy/dt = e^-t

Therefore, acceleration:

a(t) = 6t, e^-t

answer:

payment just for service  

→

$

87.12

payment for service including tax

→

$

94.09

explanation:

service only with 20% tip  

→

$

72.6

(

1

+

20

100

)

=

$

87.12

in the opening of the question the word 'service' is associated only with the pretax value.

the closing part of the question asks: how much did she pay for the  

service

−−−−−−  

so technically the answer is  

→

$

72.6

(

1

+

20

100

)

=

$

87.12

however, the intention of the question provider may have been that your answer is to be  

$

87.12

(

1

+

8

100

)

=

$

94.09

to 2 decimal places.

'

payment just for service  

→

$

87.12

payment for service including tax

→

$

94.09

tony b

mar 21, 2017

answer:

trying to explain it another way

explanation:

service charge  

.

→

$

72.60

20% tip  

20

100

×

$

72.60

=

$

14.52

−−−−−−  

←

add

$

87.12

tax  

8

100

×

$

87.12

=

$

6.97

−−−−−  

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$

94.09

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6,250

step-by-step explanation:

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to find out how many bags of fertilizer it will take, first figure out how many square feet one bag can hold. divide 1000 by 8(125) to get the unit rate(how many square feet one pound of fertilizer can hold)and multiply it by 50(6250). if i haven't made a mistake, that is the answer.