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2 years ago

Where did the negative go? 8th grade math

Mathematics

1 answer:

Ierofanga [76]2 years ago

5 0

Answer:

Since the equation is to the power of 4, the negative sign to the power of 4 will give a positive sign.

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A plumber charges $50 to make a house call. He also charges $25 per hour for labor. If the bill from the plumber is $162.50.

blsea [12.9K]

4.5 hrs because 162.50-50 = 112.50
112.50/25= 4.5

3 0

2 years ago

A competitive knitter is knitting a circular place mat. The radius of the mat is given by the formula

Ilia_Sergeevich [38]

Answer: A. $A'(t)=\frac{4356\pi}{(t+11)^{3}}-\frac{527076\pi}{(t+11)^{5}}$

B. A'(5) = 1.76 cm/s

Step-by-step explanation: Rate of change measures the slope of a curve at a certain instant, therefore, rate is the derivative.

A. Area of a circle is given by

$A=\pi.r^{2}$

So to find the rate of the area:

$\frac{dA}{dt}=\frac{dA}{dr}.\frac{dr}{dt}$

$\frac{dA}{dr} =2.\pi.r$

Using $r(t)=3-\frac{363}{(t+11)^{2}}$

$\frac{dr}{dt}=\frac{726}{(t+11)^{3}}$

Then

$\frac{dA}{dt}=2.\pi.r.[\frac{726}{(t+11)^{3}}]$

$\frac{dA}{dt}=2.\pi.[3-\frac{363}{(t+11)^{2}}].\frac{726}{(t+11)^{3}}$

Multipying and simplifying:

$\frac{dA}{dt}=\frac{4356\pi}{(t+11)^{3}} -\frac{527076\pi}{(t+11)^{5}}$

The rate at which the area is increasing is given by expression $A'(t)=\frac{4356\pi}{(t+11)^{3}} -\frac{527076\pi}{(t+11)^{5}}$ .

B. At t = 5, rate is:

$A'(5)=\frac{4356\pi}{(5+11)^{3}} -\frac{527076\pi}{(5+11)^{5}}$

$A'(5)=\frac{4356\pi}{4096} -\frac{527076\pi}{1048576}$

$A'(5)=\frac{2408693760\pi}{4294967296}$

$A'(5)=1.76268$

At 5 seconds, the area is expanded at a rate of 1.76 cm/s.

5 0

2 years ago

What is the area a a circle when the circumference is 3.50

Lapatulllka [165]

The area of the circle would be 0.97

6 0

3 years ago

Two positive integers are 3 units apart on a number line. Their product is 108. Which equation can be used to solve for m, the g

nikitadnepr [17]

If the greater integer is m, then the smaller integer must be (m-3) because the integers are 3 units apart on a number line. It cannot be in front of m, because m is the greater so it must be behind m meaning it is 3 units less. Product is the technical term for the result of a multiplication problem so m(m-3) = 108 would be the answer.

Final Answer: m(m-3) = 108

8 0

3 years ago

Read 2 more answers

The length of an object's shadow varies directly with It's heigt. If a can is 13 cm tall casts a shadow that is 7.5 cm long, a b

svetoff [14.1K]

X = Can/Bottle height, y = Shadow length
x = 13 cm, y = 7.5 cm
x = 2.5 cm, y = 14.2 cm
I'm assuming your question is asking for an equation to model this. Since there are only two data points the only equation that can be made is linear
y = mx + c
m = (y2 - y1)/(x2 - x1) <- Let 14.2 be y2, and 2.5 be x2 (it is important)
m = (14.2 - 7.5)/(2.5 - 13)
m = 6.7/-10.5
m = -0.638
y = -0.638x + c
To find c we can sub any one of the two coordinates, i'm choosing (2.5,14.2)
14.2 = -0.638(2.5) + c
14.2 = -1.595 + c
14.2 + 1.595 = c
15.795 = c
So the final equation is y = -0.638x + 15.795

6 0

2 years ago