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3 years ago

1) Which equation is true?

Mathematics

2 answers:

Olenka [21]3 years ago

8 0

The first one equals 32=16 the second one is 42=13 the third one is 30=11 so the last one is the correct answer

alina1380 [7]3 years ago

7 0

Answer:

9 x 8 = 8 x 9

Step-by-step explanation:

9 x 8 = 8 x 9

72 = 72

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A heated piece of metal cools according to the function c(x) = (.5)x − 11, where x is measured in hours. A device is added that

e-lub [12.9K]

16.5 degrees below the starting temp, whatever that is. If its 0, then -16.5 degrees.

The first equation would be (.5)5-11=-8.5, because the metal has been cooling for 5 hours.

The device that 'aids' in the cooling would be -5-3=-8, because it is a separate variable that cools the metal, so the amount the device cools is independent of the natural cooling amount, and the equation is independent of the natural cooling equation.
You then add -8.5 and -8, because the device has lowered 8.5 degrees and 8 degrees. This equals -16.5 degrees, or a decrease of 16.5 degrees.

7 0

3 years ago

Find z1z2 if z1 = 2/5(cos63° + isin63°) and z2 = 10/3(cos117° + isin117°).

Airida [17]

Answer:

-10/3 is the answer

Step-by-step explanation:

Given are two complex numbers as

$z1=\frac{2}{5} (cos63 + isin63)\\z2=\frac{10}{3} (cos 117 + isin117})$

Recall Demoivre theorem as

(cosA+isinA)(cos A+isin B) = cos(A+B)+isin(A+B)

Hence here we have sum of angles as

A+B = 63+117 =180

$z1z2=\frac{2}{5} \frac{10}{3} (cos180+isin180)$

= $\frac{-10}{3}$

Since sin180=0 and cos 180=-1

7 0

3 years ago

The rectangular model is made up of squares. Each square is of equal size.

IrinaK [193]

H 45%
you would add up the number of shaded squares and divide that by the total number of squares

6 0

2 years ago

Read 2 more answers

Amy received a $80 gift card for a coffee store. She used it in buying some coffee that cost $8.24 per pound. After buying the c

SVEN [57.7K]

Answer:

5 pounds

Step-by-step explanation:

Given that:

Amount of gift card = $80

Cost of coffee per pound = $8.24

Amount left in the card = $38.80

To find:

Number of pounds of coffee bought = ?

Solution:

Let the number of pounds of the coffee bought = $x$ pounds

Cost of 1 pound = $8.24

Cost of $x$ pounds = $8.24 $\times x$

Writing the equation as per question statement:

$80 - 8.24x = 38.80\\\Rightarrow 80 - 38.80 = 8.24x\\\Rightarrow 8.24x = 41.2\\\Rightarrow x = \dfrac{41.2}{8.24}\\\Rightarrow \bold{x = 5\ pounds}$

Therefore, 5 pounds of coffee was bought.

3 0

3 years ago

ПОЖАЛУЙСТА ПОМОГИТЕ РЕШИТЬ ДАЮ 23 ОЧКА!!!

posledela

(Простите, пожалуйста, мой английский. Русский не мой родной язык. Надеюсь, у вас есть способ перевести это решение. Если нет, возможно, прилагаемое изображение объяснит достаточно.)

Use the shell method. Each shell has a height of 3 - 3/4 y ², radius y, and thickness ∆y, thus contributing an area of 2π y (3 - 3/4 y ²). The total volume of the solid is going to be the sum of infinitely many such shells with 0 ≤ y ≤ 2, thus given by the integral

$\displaystyle 2\pi \int_0^2 y \left(3-\frac34 y^2\right) \,\mathrm dy = 2\pi \left(\frac32 y^2 - \frac3{16} y^4\right)\bigg|_0^2 = 6\pi$

Or use the disk method. (In the attachment, assume the height is very small.) Each disk has a radius of √(4/3 x), thus contributing an area of π (√(4/3 x))² = 4π/3 x. The total volume of the solid is the sum of infinitely many such disks with 0 ≤ x ≤ 3, or by the integral

$\displaystyle \pi \int_0^3 \left(\sqrt{\frac43x}\right)^2 \,\mathrm dx = \frac{2\pi}3 x^2\bigg|_0^3 = 6\pi$

Using either method, the volume is 6π ≈ 18,85. I do not know why your textbook gives a solution of 90,43. Perhaps I've misunderstood what it is you're supposed to calculate? On the other hand, textbooks are known to have typographical errors from time to time...

8 0

3 years ago