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3 years ago

14

Substitution or Elimination.

1 answer:

zimovet [89]3 years ago

5 0

It's a simultaneous equation ^^; So basically I first look at the number in front of the Y values (if they aren't the same you have to multiply each equation by the other number in front of Y in the second line and vice versa but anyways) you add the two equations if they are the same so: -3x+2y=23 + 5x+2y = -17 which should give you 2x=40 then divide by two to get x put your x answer back into the top or bottom equation (your call ^^;) and then work out what must be the Y value! I really hope this helps! ^^;

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This week, we are covering relationships that can be approximated by linear equations. For instance, y = 453x + 3768 represents

lana [24]

Answer:

See explanation below.

Step-by-step explanation:

We assume that the data is given by :

x: 30, 30, 30, 50, 50, 50, 70,70, 70,90,90,90

y: 38, 43, 29, 32, 26, 33, 19, 27, 23, 14, 19, 21.

Where X represent the cost for scholarships in thousands of dollars and y represent the cost of life for an academic semester (The data comes from the web)

We can find the least-squares line appropriate for this data.

For this case we need to calculate the slope with the following formula:

$m=\frac{S_{xy}}{S_{xx}}$

Where:

$S_{xy}=\sum_{i=1}^n x_i y_i -\frac{(\sum_{i=1}^n x_i)(\sum_{i=1}^n y_i)}{n}$

$S_{xx}=\sum_{i=1}^n x^2_i -\frac{(\sum_{i=1}^n x_i)^2}{n}$

So we can find the sums like this:

$\sum_{i=1}^n x_i = 30+30+30+50+50+50+70+70+70+90+90+90=720$

$\sum_{i=1}^n y_i =38+43+29+32+26+33+19+27+23+14+19+21=324$

$\sum_{i=1}^n x^2_i =30^2+30^2+30^2+50^2+50^2+50^2+70^2+70^2+70^2+90^2+90^2+90^2=49200$

$\sum_{i=1}^n y^2_i =38^2+43^2+29^2+32^2+26^2+33^2+19^2+27^2+23^2+14^2+19^2+21^2=9540$

$\sum_{i=1}^n x_i y_i =30*38+30*43+30*29+50*32+50*26+50*33+70*19+70*27+70*23+90*14+90*19+90*21=17540$

With these we can find the sums:

$S_{xx}=\sum_{i=1}^n x^2_i -\frac{(\sum_{i=1}^n x_i)^2}{n}=49200-\frac{720^2}{12}=6000$

$S_{xy}=\sum_{i=1}^n x_i y_i -\frac{(\sum_{i=1}^n x_i)(\sum_{i=1}^n y_i)}=17540-\frac{720*324}{12}{12}=-1900$

And the slope would be:

$m=-\frac{1900}{6000}=-0.317$

Nowe we can find the means for x and y like this:

$\bar x= \frac{\sum x_i}{n}=\frac{720}{12}=60$

$\bar y= \frac{\sum y_i}{n}=\frac{324}{12}=27$

And we can find the intercept using this:

$b=\bar y -m \bar x=27-(-0.317*60)=46.02$

So the line would be given by:

$y=-0.317 x +46.02$

We have an inverse linear relationship since the slope is negative between the variables of interest.

8 0

3 years ago

First convert these fractions to twelfths then order them.Write your

sergiy2304 [10]

Here’s the link to the answer

Curlylips444.com

8 0

3 years ago

Find the area. The figure is not drawn to scale. 7.6. 3.7

lora16 [44]

Answer:

28.12

Step-by-step explanation:

6 0

3 years ago

Haos dog ate 40 cns of dog food in 31 day. how many cans should hao buy to feed his dog in 6 days

Crank

The answer is 8. 40 / 31 = 1.29032258. Multiply that by 6 and you have 7.74193548. Round up because you can't buy 7.7 cans of dog food.

7 0

3 years ago

What is eight tenths -five tenths?

kondor19780726 [428]

Eight tenths minus five tenths equals three tenths.

6 0

3 years ago