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3 years ago

Evaluate 3xy²-y³ for x=-1 and y=2.help.

Mathematics

2 answers:

yanalaym [24]3 years ago

7 0

The answer to this problem is -20

Annette [7]3 years ago

7 0

Step-by-step explanation:

=3xy²-y³

=3(-1)(2)²-(2)³

=3(-1)(4)-(8)

= -12-8

= -20

hope it helps.

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What is the area?

Vika [28.1K]

27 because 6*9 is 54,54 divided by 2 is 26

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3 years ago

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Set A of six numbers has a standard deviation of 3 and set B of four numbers has a standard deviation of 5. Both sets of numbers

Alenkinab [10]

Given:

$\sigma_A=3$

$n_A=6$

$\sigma_B=5$

$n_B=4$

$\overline{x}_A=\overline{x}_B$

To find:

The variance. of combined set.

Solution:

Formula for variance is

$\sigma^2=\dfrac{\sum (x_i-\overline{x})^2}{n}$ ...(i)

Using (i), we get

$\sigma_A^2=\dfrac{\sum (x_i-\overline{x}_A)^2}{n_A}$

$(3)^2=\dfrac{\sum (x_i-\overline{x}_A)^2}{6}$

$9=\dfrac{\sum (x_i-\overline{x}_A)^2}{6}$

$54=\sum (x_i-\overline{x}_A)^2$

Similarly,

$\sigma_B^2=\dfrac{\sum (x_i-\overline{x}_B)^2}{n_B}$

$(5)^2=\dfrac{\sum (x_i-\overline{x}_B)^2}{4}$

$25=\dfrac{\sum (x_i-\overline{x}_B)^2}{4}$

$100=\sum (x_i-\overline{x}_B)^2$

Now, after combining both sets, we get

$\sigma^2=\dfrac{\sum (x_i-\overline{x}_A)^2+\sum (x_i-\overline{x}_B)^2}{n_A+n_B}$

$\sigma^2=\dfrac{54+100}{6+4}$

$\sigma^2=\dfrac{154}{10}$

$\sigma^2=15.4$

Therefore, the variance of combined set is 15.4.

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3 years ago

Please show steps to solve y=3\2x-2 y=x+2

castortr0y [4]

Substitute what you know y is equal to into the equation:
y = x + 2
3/2x - 2 = x + 2

Then you can simplify your equation by multiplying both sides by 2 to eliminate the fraction which will give you:

3x - 4 = 2x + 4

Add the -4 to the other side to get 8 and subtract the 2x from the 3x so you have:

x = 8 Now solve for y by substituting your value for x into the other equation:
y = 3/2(8) - 2 Simplify by combining your numbers and you get:
y = 10 Check your answer by substituting y and x into the original equation:
(10) = (8) - 2
Correctly done! So your answers are x = 8 and y = 10

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4 years ago

A=2πr solve for π‍‍‍

pishuonlain [190]

$A=2\pi r\\\\2\pi r=A\ \ \ \ |divide\ both\ sides\ by\ 2r\\\\\boxed{\pi=\frac{A}{2r}}$

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3 years ago

1. Six more than four times a number is eighteen.<br> What is the number?

saw5 [17]

Answer:

Step-by-step explanation:

1. Write out the equation

6 + 4x = 18

2. Subtract 6 from each side

4x = 12

3. Divide by 4 on each side

x = 3

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4 years ago

Evaluate 3xy²-y³ for x=-1 and y=2.help.​

Evaluate 3xy²-y³ for x=-1 and y=2.help.