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3 years ago

Please help me on this question (7th grade math) show your work

Mathematics

1 answer:

lakkis [162]3 years ago

6 0

You can take two of the x and y on the table to find the slope:

y2 - y1 / x2 - x1

Lets use (3, 12) and (4, 15)

15 - 12 / 4 - 3

3/1

The slope is 3

Now you can use the point-slope formula to find the equation: y - y1 = m(x - x1)

y - 9 = 3(x - 2)

y - 9 = 3x -6

y = 3x + 3

So you are correct with choice B.

Hope this helped! Mark as Brainliest Please! :)))

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What is 12 1/4`÷7/8

Sidana [21]

Answer:

Divide

12 and 1 over 412

÷ 7 over 8

= 392 over 28

392

Step 1 of 2: Divide, sub-step a: Convert mixed number to improper fraction.

Convert mixed number to improper fraction

12 and 1 over 412

= ( 12 × 4 ) over 4

12 × 4

+ 1 over 4

= ( 48 + 1 ) over 4

48 + 1

= 49 over 4

Step 1 of 2: Divide, sub-step b: Divide.

Divide

49 over 4

÷ 7 over 8

= 49 over 4

× 8 over 7

= ( 49 × 8 ) over ( 4 × 7 )

49 × 8

4 × 7

= 392 over 28

392

To divide fractions, invert the second one (turn it upside-down), then multiply the numerators and denominators.Divide

12 and 1 over 412

÷ 7 over 8

= 392 over 28

392

Step 1 of 2: Divide, sub-step a: Convert mixed number to improper fraction.

Convert mixed number to improper fraction

12 and 1 over 412

= ( 12 × 4 ) over 4

12 × 4

+ 1 over 4

= ( 48 + 1 ) over 4

48 + 1

= 49 over 4

Step 1 of 2: Divide, sub-step b: Divide.

Divide

49 over 4

÷ 7 over 8

= 49 over 4

× 8 over 7

= ( 49 × 8 ) over ( 4 × 7 )

49 × 8

4 × 7

= 392 over 28

392

To divide fractions, invert the second one (turn it upside-down), then multiply the numerators and denominators.

4 0

3 years ago

In a study published on January 31, 2011 in The Proceedings of the National Academy of Sciences, researchers randomly assigned 1

Kaylis [27]

Answer:

Step-by-step explanation:

Hello!

The objective of this test is to know if aerobic exercise modifies hippocampus activity. A random sample of 120 elderly men and women was taken and divided into two groups.

Group 1: Walked around a track three times a week.

Group 2: Did a variety of less aerobic exercises, including yoga and resistance training with bands.

After a year their brains were scanned showing that group 1 had an increase of 2% in their hippocampus and group 2 showed a decrease of 1.4%

a. True, this type of observational study can be the prelude to a more formal statistical study.

b. True, the explanatory variable is "type of exercise", it's the variable that the investigator suspects influence the hippocampus volume.

c. True, the objective of this experiment is to test if there is any modification on hippocampus volume, that's why the volume of the hippocampus was measured, before and after a year of exercise.

d. False, this is an observational study, you cannot establish a causal relationship between the two variables. Just inform you that there seems to be an association. To be able to generalize the results to all elderly population you need a more formal statistical experiment to support your conclusions.

I hope it helps!

5 0

3 years ago

Find the mass and center of mass of the lamina that occupies the region D and has the given density function rho. D is the trian

Alla [95]

Answer: mass (m) = 4 kg

center of mass coordinate: (15.75,4.5)

Step-by-step explanation: As a surface, a lamina has 2 dimensions (x,y) and a density function.

The region D is shown in the attachment.

From the image of the triangle, lamina is limited at x-axis: 0≤x≤2

At y-axis, it is limited by the lines formed between (0,0) and (2,1) and (2,1) and (0.3):

Points (0,0) and (2,1):

y = $\frac{1-0}{2-0}(x-0)$

y = $\frac{x}{2}$

Points (2,1) and (0,3):

y = $\frac{3-1}{0-2}(x-0) + 3$

y = -x + 3

Now, find total mass, which is given by the formula:

$m = \int\limits^a_b {\int\limits^a_b {\rho(x,y)} \, dA }$

Calculating for the limits above:

$m = \int\limits^2_0 {\int\limits^a_\frac{x}{2} {2(x+y)} \, dy \, dx }$

where a = -x+3

$m = 2.\int\limits^2_0 {\int\limits^a_\frac{x}{2} {(xy+\frac{y^{2}}{2} )} \, dx }$

$m = 2.\int\limits^2_0 {(-x^{2}-\frac{x^{2}}{2}+3x )} \, dx }$

$m = 2.\int\limits^2_0 {(\frac{-3x^{2}}{2}+3x)} \, dx }$

$m = 2.(\frac{-3.2^{2}}{2}+3.2-0)$

m = 2(-4+6)

m = 4

Mass of the lamina that occupies region D is 4.

Center of mass is the point of gravity of an object if it is in an uniform gravitational field. For the lamina, or any other 2 dimensional object, center of mass is calculated by:

$M_{x} = \int\limits^a_b {\int\limits^a_b {y.\rho(x,y)} \, dA }$