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dsp73
3 years ago
10

Complete the square: x^2-8x+21=6 Please show work

Mathematics
2 answers:
laila [671]3 years ago
7 0

........................

mina [271]3 years ago
5 0

Answer:

x=5 and 3

Step-by-step explanation:

x^2-8x+21=6

x^2-8x+21+16=6+16

(x-4)^2=1

(x-4)=±1, x=5 and 3

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Solve the following System of Three Equations: x−3y+z=−15<br> 2x+y−z=−2<br> x+y+2z=1
jeyben [28]

Answer:

x = -3 , y = 4 , z = 0

Step-by-step explanation:

Solve the following system:

{x - 3 y + z = -15

2 x + y - z = -2

x + y + 2 z = 1

Hint: | Choose an equation and a variable to solve for.

In the first equation, look to solve for z:

{x - 3 y + z = -15

2 x + y - z = -2

x + y + 2 z = 1

Hint: | Solve for z.

Subtract x - 3 y from both sides:

{z = 3 y + (-x - 15)

2 x + y - z = -2

x + y + 2 z = 1

Hint: | Perform a substitution.

Substitute z = -15 - x + 3 y into the second and third equations:

{z = -15 - x + 3 y

15 + 3 x - 2 y = -2

x + y + 2 (-15 - x + 3 y) = 1

Hint: | Expand the left hand side of the equation x + y + 2 (-15 - x + 3 y) = 1.

x + y + 2 (-15 - x + 3 y) = x + y + (-30 - 2 x + 6 y) = -30 - x + 7 y:

{z = -15 - x + 3 y

15 + 3 x - 2 y = -2

-30 - x + 7 y = 1

Hint: | Choose an equation and a variable to solve for.

In the second equation, look to solve for x:

{z = -15 - x + 3 y

15 + 3 x - 2 y = -2

-30 - x + 7 y = 1

Hint: | Isolate terms with x to the left hand side.

Subtract 15 - 2 y from both sides:

{z = -15 - x + 3 y

3 x = 2 y - 17

-30 - x + 7 y = 1

Hint: | Solve for x.

Divide both sides by 3:

{z = -15 - x + 3 y

x = (2 y)/3 - 17/3

-30 - x + 7 y = 1

Hint: | Perform a substitution.

Substitute x = (2 y)/3 - 17/3 into the third equation:

{z = -15 - x + 3 y

x = (2 y)/3 - 17/3

(19 y)/3 - 73/3 = 1

Hint: | Choose an equation and a variable to solve for.

In the third equation, look to solve for y:

{z = -15 - x + 3 y

x = (2 y)/3 - 17/3

(19 y)/3 - 73/3 = 1

Hint: | Isolate terms with y to the left hand side.

Add 73/3 to both sides:

{z = -15 - x + 3 y

x = (2 y)/3 - 17/3

(19 y)/3 = 76/3

Hint: | Solve for y.

Multiply both sides by 3/19:

{z = -15 - x + 3 y

x = (2 y)/3 - 17/3

y = 4

Hint: | Perform a back substitution.

Substitute y = 4 into the first and second equations:

{z = -x - 3

x = -3

y = 4

Hint: | Perform a back substitution.

Substitute x = -3 into the first equation:

{z = 0

x = -3

y = 4

Hint: | Sort results.

Collect results in alphabetical order:

Answer: {x = -3 , y = 4 , z = 0

6 0
3 years ago
What is the slope of the line represented by the equation y = – 2/3- 5x?
saveliy_v [14]
-5 i think.....................
4 0
3 years ago
Read 2 more answers
Three plus the reciprocal of a number equals 7 divided by that number. What is the number?
tester [92]
3+1/x *x = 7/x*x
3x+1 = 7
3x+1-1=7-1
3x=6
3x/3 =6/3
x =2


3 0
3 years ago
Find the length of the third side. If necessary, round to the nearest tenth.<br> 6<br> 14
Romashka-Z-Leto [24]

Answer:

≈ 12.6

Step-by-step explanation:

Using Pythagoras' identity in the right triangle.

The square on the hypotenuse is equal to the sum of the squares on the other 2 sides.

let x be the third side, then

x² + 6² = 14²

x² + 36 = 196 ( subtract 36 from both sides )

x² = 160 ( take the square root of both sides )

x = \sqrt{160} ≈ 12.6 ( to the nearest tenth )

8 0
3 years ago
Question 12
klasskru [66]
Mr. Jones's prescription calls for 1.04 tablets per day. Based on this information, how many tablets should Mr. Jones take per day? a) 1.25 O b) 1.5 c) 10 d) 2
3 0
2 years ago
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