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elena-s [515]
3 years ago
9

Katalin drove 210 miles on her vacation. She drove an average of 1.4 times faster on the second 105 miles of her trip than she d

id on the first 105 miles of her trip. Which expression represents the time she spent driving? Let x = her speed on the first half of the trip.
A. 180x

B. 360 divided by x.

C. 252 divided by x.

D. 180 divided by x.
Mathematics
1 answer:
konstantin123 [22]3 years ago
5 0

The answer is D. 180 divided by x. .


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What is the radius of a circle whose equation is x^2+y^2-10x+6y + 18=0
rjkz [21]

Answer:

Explanation:

We must write this equation in the form

(

x

−

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+

(

y

−

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2

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Where

(

a

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are the co ordinates of the center of the circle and the radius is

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So the equation is

x

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x

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6

y

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18

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Complete the squares so add 25 on both sides of the equation

x

2

+

y

2

−

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x

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+

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y

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=

0

+

25

=

(

x

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2

+

y

2

+

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y

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Now add 9 on both sides

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2

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y

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(

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(

y

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3

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2

+

18

=

0

+

25

+

9

This becomes

(

x

−

5

)

2

+

(

y

+

3

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2

=

16

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−

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or 4

6 0
3 years ago
an inverted conical water tank with a height of 20 ft and a radius of 8 ft is drained through a hole in the vertex (bottom) at a
viktelen [127]

Answer:

the rate of change of the water depth when the water depth is 10 ft is;  \mathbf{\dfrac{dh}{dt}  = \dfrac{-25}{100  \pi} \  \ ft/s}

Step-by-step explanation:

Given that:

the inverted conical water tank with a height of 20 ft and a radius of 8 ft  is drained through a hole in the vertex (bottom) at a rate of 4 ft^3/sec.

We are meant to find the  rate of change of the water depth when the water depth is 10 ft.

The diagrammatic expression below clearly interprets the question.

From the image below, assuming h = the depth of the tank at  a time t and r = radius of the cone shaped at a time t

Then the similar triangles  ΔOCD and ΔOAB is as follows:

\dfrac{h}{r}= \dfrac{20}{8}    ( similar triangle property)

\dfrac{h}{r}= \dfrac{5}{2}

\dfrac{h}{r}= 2.5

h = 2.5r

r = \dfrac{h}{2.5}

The volume of the water in the tank is represented by the equation:

V = \dfrac{1}{3} \pi r^2 h

V = \dfrac{1}{3} \pi (\dfrac{h^2}{6.25}) h

V = \dfrac{1}{18.75} \pi \ h^3

The rate of change of the water depth  is :

\dfrac{dv}{dt}= \dfrac{\pi r^2}{6.25}\  \dfrac{dh}{dt}

Since the water is drained  through a hole in the vertex (bottom) at a rate of 4 ft^3/sec

Then,

\dfrac{dv}{dt}= - 4  \ ft^3/sec

Therefore,

-4 = \dfrac{\pi r^2}{6.25}\  \dfrac{dh}{dt}

the rate of change of the water at depth h = 10 ft is:

-4 = \dfrac{ 100 \ \pi }{6.25}\  \dfrac{dh}{dt}

100 \pi \dfrac{dh}{dt}  = -4 \times 6.25

100  \pi \dfrac{dh}{dt}  = -25

\dfrac{dh}{dt}  = \dfrac{-25}{100  \pi}

Thus, the rate of change of the water depth when the water depth is 10 ft is;  \mathtt{\dfrac{dh}{dt}  = \dfrac{-25}{100  \pi} \  \ ft/s}

4 0
3 years ago
a certain number of yams is sufficient to feed 20 students for 12 days for how many days would the same number of yams feed 15 s
Softa [21]

Step-by-step explanation:

no of days = (15×12)/20= 9 days

I hope this helps

6 0
3 years ago
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Could anyone help me with this? (A question I've been wondering about.)
Kamila [148]
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5 0
3 years ago
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2 + 3 × (8 + 53 ÷ 1)<br><br> Can please include the working to it. Thank you,
luda_lava [24]

Step-by-step explanation:

2 + 3 × (8 + 53 ÷ 1)

we first work out the equation in the brackets

so...

(8 + 53 ÷ 1)

division comes first so we divide 53÷1 which is 1 so the equation looks like this:

(8+53)

we work this out and get

61

then we work the rest out

2 + 3 × <u>61</u>

multiplication comes first so...

3×61= 183

and

2+ 183= 185

Therefore 2 + 3 × (8 + 53 ÷ 1)= <u>185</u>

Hope this helped- have a good day bro cya)

6 0
2 years ago
Read 2 more answers
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