All categories

4 years ago

Problem 1 3x + y = –14 -2x-y=9

Mathematics

1 answer:

Radda [10]4 years ago

3 0

Answer:

x = -5 , y = 1

Step-by-step explanation:

Solve the following system:

{3 x + y = -14 | (equation 1)

-2 x - y = 9 | (equation 2)

Add 2/3 × (equation 1) to equation 2:

{3 x + y = -14 | (equation 1)

0 x - y/3 = (-1)/3 | (equation 2)

Multiply equation 2 by -3:

{3 x + y = -14 | (equation 1)

0 x+y = 1 | (equation 2)

Subtract equation 2 from equation 1:

{3 x+0 y = -15 | (equation 1)

0 x+y = 1 | (equation 2)

Divide equation 1 by 3:

{x+0 y = -5 | (equation 1)

0 x+y = 1 | (equation 2)

Collect results:

Answer: {x = -5 , y = 1

You might be interested in

What is 10 divided by 2

const2013 [10]

The answer is 5. Take 10 and divide that into 2 groups equally.

8 0

3 years ago

Read 2 more answers

Two lines, C and D, are represented by the following equations: Line C: y = x + 5 Line D: y = −2x − 1 Which of the following opt

marin [14]

Answer:

The correct answer is B

Step-by-step explanation:

I know this is the answer because I took the test and got it right.

3 0

3 years ago

What is the measure of RST? A. 72° B. 324° C. 162° D. 81°

larisa [96]

The answer is D 81 that the answer to the question

5 0

3 years ago

If I eat 20 cupcakes and A=chicken nuggies what color is the imposter? True or false. extra points if you explain your answer.

podryga [215]

Answer:

true

Step-by-step explanation:

because your susy

7 0

3 years ago

"Select the equation of the least squares line for the data: (34.0, 1.30), (32.5, 3.25), (35.0, .65), (31.0, 6.50), (30.0, 5.85)

yulyashka [42]

Answer:

$y=-1.055 x +37.643$

And the best option would be:

a. ŷ= 37.643-1.0543x

Step-by-step explanation:

We assume that the data is this one:

x: 34.0, 32.5, 35.0, 31.0, 30.0, 27.5, 29.0

y: 1.30, 3.25, 0.65, 6.50, 5.85, 8.45, 6.50

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:

$\sum_{i=1}^n x_i = 34.0+ 32.5+ 35.0+ 31.0+ 30.0+ 27.5+ 29.0
=219$

$\sum_{i=1}^n y_i =1.3+3.25+0.65+6.5+5.85+8.45+6.5=32.5$

$\sum_{i=1}^n x^2_i = 34.0^2+ 32.5^2+ 35.0^2+ 31.0^2+ 30.0^2+ 27.5^2+ 29.0^2
=6895.5$

$\sum_{i=1}^n y^2_i =1.3^2+3.25^2+0.65^2+6.5^2+5.85^2+8.45^2+6.5^2=202.8$

$\sum_{i=1}^n x_i y_i =34*1.3 + 32.5*3.25+ 35*0.65+ 31*6.5+30*5.585 +27.5*8.45 +29*6.5=970.45$

With these we can find the sums:

$S_{xx}=\sum_{i=1}^n x^2_i -\frac{(\sum_{i=1}^n x_i)^2}{n}=6895.5-\frac{219^2}{7}=43.929$

$S_{xy}=\sum_{i=1}^n x_i y_i -\frac{(\sum_{i=1}^n x_i)(\sum_{i=1}^n y_i)}{n}=970.45-\frac{219*32.5}{7}=-46.336$

And the slope would be:

$m=-\frac{46.336}{43.929}=-1.055$

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

$\bar x= \frac{\sum x_i}{n}=\frac{219}{7}=31.286$

$\bar y= \frac{\sum y_i}{n}=\frac{32.5}{7}=4.643$

And we can find the intercept using this:

$b=\bar y -m \bar x=4.643-(-1.055*31.286)=37.643$

So the line would be given by:

$y=-1.055 x +37.643$

And the best option would be:

a. ŷ= 37.643-1.0543x

5 0

4 years ago