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Airida [17]
3 years ago
6

Solve the system by substitution. (Please Explain how you did it Ill give brainliest)

Mathematics
1 answer:
antoniya [11.8K]3 years ago
4 0

Answer:

{x,y,z} = {0,13,20}

Step-by-step explanation:

{x,y,z} = {0,13,20}  

 

System of Linear Equations entered :

  [1]    x + y - z = -7

  [2]    2x - y + z = 7

  [3]    x - 4y + 3z = 8

Solve by Substitution :

// Solve equation [3] for the variable  x  

 

 [3]    x = 4y - 3z + 8

// Plug this in for variable  x  in equation [1]

  [1]    (4y-3z+8) + y - z = -7

  [1]    5y - 4z = -15

// Plug this in for variable  x  in equation [2]

  [2]    2•(4y-3z+8) - y + z = 7

  [2]    7y - 5z = -9

// Solve equation [2] for the variable  y  

 

 [2]    7y = 5z - 9

 [2]    y = 5z/7 - 9/7

// Plug this in for variable  y  in equation [1]

  [1]    5•(5z/7-9/7) - 4z = -15

  [1]     - 3z/7 = -60/7

  [1]     - 3z = -60

// Solve equation [1] for the variable  z  

  [1]    3z = 60  

  [1]    z = 20  

// By now we know this much :

   x = 4y-3z+8

   y = 5z/7-9/7

   z = 20

// Use the  z  value to solve for  y  

   y = (5/7)(20)-9/7 = 13  

// Use the  y  and  z  values to solve for  x  

 x = 4(13)-3(20)+8 = 0

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There are 35 boys in the sixth grade. The number of girls in the sixth grade is 40.
Wewaii [24]

Answer:

London is correct

Step-by-step explanation:

We can find the ratio by dividing the ratio of 35:40 by both of the number's greatest common factor. A factor is a number that can be multiplied with another number to get the desired number. The greatest common factor of the two numbers is 5, so dividing both numbers by 5 leaves you with the ratio of 7:8. Hope this helps friend.

4 0
2 years ago
Using the graph below, what is the best estimate of month 7's average temperature if the equation for the line of best fit is y
defon

Substitute x to be 7 (for month 7) and work out the equation:

y = -13(7) + 111

y = -91 + 111

y = 20

Your answer is 20 degrees Fahrenheit.

5 0
3 years ago
Read 2 more answers
What is the lateral area of a regular square pyramid if the base edges are of length 24 and perpendicular height is 5?
iren2701 [21]

Answer:

The lateral area is 624 unit²

Step-by-step explanation:

* Lets explain how to solve the problem

- The regular square pyramid has a square base and four congruent

 triangles

- The slant height of it = \sqrt{(\frac{1}{2}b)^{2}+h^{2}}, where

  b is the length of its base and h is the perpendicular height

- Its lateral area = \frac{1}{2}.p.l, p is the perimeter of the base

 and l is the slant height

* Lets solve the problem

∵ The base of the pyramid is a square with side length 24 units

∵ Its perpendicular height is 5 units

∵ The slant height (l) = \sqrt{(\frac{1}{2}b)^{2}+h^{2}}

∴ l = The slant height of it = \sqrt{(\frac{1}{2}.24)^{2}+5^{2}}

∴ l = \sqrt{(12)^{2}+25}=\sqrt{144+25}=\sqrt{169}=13

∴ l = 13 units

∵ Perimeter of the square = b × 4

∴ The perimeter of the base (p) = 24 × 4 = 96 units

∵ The lateral area = \frac{1}{2}.p.l

∴ The lateral area = \frac{1}{2}.(96).(13)

∴ The lateral area = 624 unit²

* The lateral area is 624 unit²

4 0
3 years ago
Find the surface area.<br> 7 in.<br> 7 in.<br> 7 in.<br> please help
saveliy_v [14]

Answer:

294

Step-by-step explanation:

One side is 7×7 which is 49.

There are six sides so now it's 49×6, which gives you 294.

6 0
2 years ago
Round the following to the nearest hundreds. 23457,45289,2458​
djverab [1.8K]

I think it's 23500, 45300, 2500

4 0
3 years ago
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