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xz_007 [3.2K]
4 years ago
12

−8x + 3y = 21 solve it

Mathematics
2 answers:
Nataly [62]4 years ago
6 0
So first we have to subtract 3y from 21 cause the oppisit of addition which is subtraction so you get 18y when we divide that with -8y and get y=2.25y
tamaranim1 [39]4 years ago
5 0
-8x + 3y = 21
-8x + 8x + 3y = 21 + 8x
<u>3y</u> = <u>21 + 8x</u>
 3          3
  y = 7 + 2 2/3x
-8x + 3(7 + 2 2/3x) = 21
-8x + 21 + 8x = 21
-8x + 8x + 21 = 21
0x + 21 = 21
0x + 21 - 21 = 21 - 21
<u>0x</u> = <u>0</u>
 0     0
  x = 0
-8(0) + 3y = 21
0 + 3y = 21
<u>3y</u> = <u>21</u>
 3      3
  y = 7
(x, y) = (0. 7)
-----------------------------------------------------------------------------------------------
-8x + 3y = 21
-8x + 3y - 3y = 21 - 3y
<u>-8x</u> = <u>21 - 3y</u>
 -8         -8
   x = -2 5/8 + 3/8y
-8(-2 5/8 + 3/8y) + 3y = 21
21 - 3y + 3y = 21
21 - 0y = 21
21 - 21 - 0y = 21 - 21
<u>-0y</u> =<u> 0</u>
 -0    -0
   y = 0
-8x + 3(0) = 21
-8x + 0 = 21
<u>-8x</u> = <u>21</u>
 -8     -8
   x = -2 5/8
(x, y) = (-2 5/8, 0)
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Ann [662]

Answer:

t=\frac{1.20-1.25}{\frac{0.14}{\sqrt{49}}}=-2.50    

Step-by-step explanation:

Data given and notation  

\bar X=1.20 represent the sample mean given

\sigma = 0.14 represent the population standard deviation

n=49 sample size  

\mu_o =1.25 represent the value that we want to test

t would represent the statistic (variable of interest)  

State the null and alternative hypotheses.  

We need to conduct a hypothesis in order to check if the true mean for the gasoline prices is lower than 1.25, the system of hypothesis would be:  

Null hypothesis:\mu \geq 1.25  

Alternative hypothesis:\mu < 1.25  

If we analyze the size for the sample is > 30 but we don't know the population deviation so is better apply a t test to compare the actual mean to the reference value, and the statistic is given by:  

t=\frac{\bar X-\mu_o}{\frac{s}{\sqrt{n}}}  (1)  

Calculate the statistic

We can replace in formula (1) the info given like this:  

t=\frac{1.20-1.25}{\frac{0.14}{\sqrt{49}}}=-2.50    

5 0
3 years ago
15 times 25 is equal to
user100 [1]
15 * 25 = 375 <=== simple multiplication
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admissions to a carnival is $5 and each game at the carnival costs 0.85 you have $15 to spend on admissions and games what is th
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2007 Federal Income Tax Table
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Answer:

Tax= $ 7,173.5

Step-by-step explanation:

Her taxable income is $ 43,000 which lies in the tax category $ 31,850 to

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Step-by-step explanation:

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3 years ago
What is the length of the unknown leg in the right triangle?
ella [17]

Answer:

i dont understand your question really, but to solve it you would use the equation a^2+b^2=c^2 and c^2 is the hypotenuse and a and b are the other sides (doesn't matter what order) so if the hypotenuse is 8 and the side length  is 73 and the missing side is a then you would use the equation, a^2+8=73

Step-by-step explanation:

read the above and hope this helps a little :)

8 0
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