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3 years ago

What is the equation to -2x-9=-89

Mathematics

2 answers:

Oksana_A [137]3 years ago

7 0

Step-by-step explanation:

I'm guessing you mean answer?

You would need to solve for x.

Steps:

1. -2x-9=-89

--add 9 to both sides

2. -2x=-80

--divide each side by -2

3. x=40

Hope this helped!! :))

inna [77]3 years ago

6 0

The answer for X is 40

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The circumference of a sphere was measured to be 80 cm with a possible error of 0.5 cm. A) Use differentials to estimate the max

siniylev [52]

Answer:

A) The maximum error in the calculated surface area: $25cm^2$

Relative error: $0.013$

B) The maximum error in the calculated volume: $162cm^2$

Relative error: $0.019$

Step-by-step explanation:

A) The formula for the surface area is:

$A=4\pi r^2$

The measured value is the circumference which is equal to:

$C=2\pi r$

then the radius is:

$r=\frac{C}{2\pi}$

Substituting in the formula of the surface:

$A=4\pi(\frac{C}{2\pi})^2\\A=4\pi(\frac{C^2}{4\pi^2})\\A=\frac{C^2}{\pi}$

Using the formula to calculate the error:

$dy=f'(x)dx$

Where $x$ is the variable measured and $y$ is a function of $x$ ( $y=f(x)$ ).

$dA=f'(C)dC\\dA=\frac{2C^{(2-1)}}{\pi}dC\\dA=\frac{2C}{\pi}dC$

We have C=80cm and dC=0.5cm

$dA=\frac{2C}{\pi}dC\\dA=\frac{2(80)}{\pi}(0.5)\\dA=\frac{160}{\pi}(0.5)\\dA=50.9296(0.5)\\dA=25.4648\approx25cm^2$

The relative error is the maximum error divide by the total area. The total area is: $A=\frac{C^2}{\pi}=\frac{(80)^2}{\pi}=\frac{6400}{\pi}=2037.1833cm^2$

$\frac{dA}{A}=\frac{25.4648}{2037.1833} =0.0125\approx0.013$

B) The formula for the volume is:

$V=\frac{4}{3} \pi r^3$

Using $r=\frac{C}{2\pi}$

$V=\frac{4}{3} \pi r^3\\V=\frac{4}{3} \pi (\frac{C}{2\pi})^3\\V=\frac{4}{3} \pi (\frac{C^3}{8\pi^3})\\V=\frac{1}{3}(\frac{C^3}{2\pi^2})\\V=\frac{C^3}{6\pi^2}$

The maximum error is:

$dV=\frac{3C^{3-1}}{6\pi^2}dC\\dV=\frac{C^{2}}{2\pi^2}dC\\dV=\frac{(80)^{2}}{2\pi^2}(0.5)\\dV=\frac{6400}{2\pi^2}(0.5)\\dV=\frac{6400}{2\pi^2}(0.5)\\dV=(324.2278)(0.5)\\dV=162.1139\approx162cm^2$

The calculated volume is:

$V=\frac{C^3}{6\pi^2}\\V=\frac{(80)^3}{6\pi^2}\\V=\frac{512000}{6\pi^2}\\V=8646.0743$

The relative error is:

$\frac{dV}{V}=\frac{162.1139}{8646.0743}=0.0188\approx0.019$

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2 years ago

If 75% of a number is 15, 15% of that number

natta225 [31]

Answer:

Step-by-step explanation:

0.75 x ? = 15

? = 15/0.75 = 20

15% of 20 = 3

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2 years ago

two runners start 30kilometer apart and run toward each other. they meet after 3hours. One Runner runs 2 kilometers per hour fas

belka [17]

Let the slower runners speed be X kilometers per hour.

Then the faster runners speed would be X+2 kilometers per hour.

The formula for distance is Speed times time.

The distance is given as 30 kilometers and time is given as 3 hours.

Since there are two runners you need to add the both of them together.

The equation becomes 30 = 3x + 3(x+2)

Now solve for x:

30 = 3x + 3(x+2)

Simplify:

30 = 3x + 3x +6

30 = 6x + 6

Subtract 6 from each side:

24 = 6x

Divide both sides by 6:

x = 24/6

x = 4

The slower runner ran at 4 kilometers per hour.

The faster runner ran at 4+2 = 6 kilometers per hour.

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2 years ago

Need help understanding this question

harkovskaia [24]

Answer:

-9<x≤2

Step-by-step explanation:

The domain is the x values

If we look at the line, we see a closed circle when x=2, so x is less than or equal to 2

The other circle is open and is at -9, so x is greater than -9

-9<x≤2

Lemme know if u need more explanation!

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2 years ago

Find the circumference and area of a circle with a diameter of 22 inches. Leave your answers in terms of pi.

astra-53 [7]

The circumference formula is
C=Diameter x π=22 x π, the area formula is A=π x R²
or R=D/2=22/2=11

the answer is d. C = 22π; A = 121π

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3 years ago

Read 2 more answers