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lana66690 [7]
3 years ago
7

Whats 42+87? Now, answer with tik to.k me mes

Mathematics
2 answers:
drek231 [11]3 years ago
8 0

Answer:

21

Step-by-step explanation:

I'm 100% sure it's 21 jsgsisbskwnos

Alisiya [41]3 years ago
4 0

Answer:

129

Step-by-step explanation:

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Jonathan purchased 30 markers for $5.40. What is the price per marker?
madreJ [45]

Answer: 0.18 is your answer

Step-by-step explanation:

3 0
2 years ago
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A punch glass is in the shape of a hemisphere with a radius of 5 cm. If the punch is being poured into the glass so that the cha
Galina-37 [17]

Answer:

28.27 cm/s

Step-by-step explanation:

Though Process:

  • The punch glass (call it bowl to have a shape in mind) is in the shape of a hemisphere
  • the radius r=5cm
  • Punch is being poured into the bowl
  • The height at which the punch is increasing in the bowl is \frac{dh}{dt} = 1.5
  • the exposed area is a circle, (since the bowl is a hemisphere)
  • the radius of this circle can be written as 'a'
  • what is being asked is the rate of change of the exposed area when the height h = 2 cm
  • the rate of change of exposed area can be written as \frac{dA}{dt}.
  • since the exposed area is changing with respect to the height of punch. We can use the chain rule: \frac{dA}{dt} = \frac{dA}{dh} . \frac{dh}{dt}
  • and since A = \pi a^2 the chain rule above can simplified to \frac{da}{dt} = \frac{da}{dh} . \frac{dh}{dt} -- we can call this Eq(1)

Solution:

the area of the exposed circle is

A =\pi a^2

the rate of change of this area can be, (using chain rule)

\frac{dA}{dt} = 2 \pi a \frac{da}{dt} we can call this Eq(2)

what we are really concerned about is how a changes as the punch is being poured into the bowl i.e \frac{da}{dh}

So we need another formula: Using the property of hemispheres and pythagoras theorem, we can use:

r = \frac{a^2 + h^2}{2h}

and rearrage the formula so that a is the subject:

a^2 = 2rh - h^2

now we can derivate a with respect to h to get \frac{da}{dh}

2a \frac{da}{dh} = 2r - 2h

simplify

\frac{da}{dh} = \frac{r-h}{a}

we can put this in Eq(1) in place of \frac{da}{dh}

\frac{da}{dt} = \frac{r-h}{a} . \frac{dh}{dt}

and since we know \frac{dh}{dt} = 1.5

\frac{da}{dt} = \frac{(r-h)(1.5)}{a}

and now we use substitute this \frac{da}{dt}. in Eq(2)

\frac{dA}{dt} = 2 \pi a \frac{(r-h)(1.5)}{a}

simplify,

\frac{dA}{dt} = 3 \pi (r-h)

This is the rate of change of area, this is being asked in the quesiton!

Finally, we can put our known values:

r = 5cm

h = 2cm from the question

\frac{dA}{dt} = 3 \pi (5-2)

\frac{dA}{dt} = 9 \pi cm/s// or//\frac{dA}{dt} = 28.27 cm/s

5 0
3 years ago
Line p goes through points (-2,6) and (4, -3). What is the equation of line p?
vekshin1
1+1.....................
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3 years ago
Which three test points could be used to draw the graph of the solutions to<br> x² + 4x-3&gt;0
hram777 [196]

(2,2),(3,1),(5,2)

---

hope it helps

8 0
3 years ago
Anna bought a sweater at 40% off the original price. If she paid $12, what was the original price of the sweater?
Snezhnost [94]

Answer:

The original cost was 20 dollars.

Step-by-step explanation:

$12 represents 60% of the original price.

Set up a proportion

  • 60/100 = 12
  • 100% = x

Cross multiply Reduce 100/100 to 1

60/100 * x = 12 * 100/100

Multiply by 100

60/ 100 * x = 12

Divide by 60

60x = 12*100

60x = 1200                                      

60x/60 = 1200/60

x = 20 dollars.

3 0
3 years ago
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