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shtirl [24]
3 years ago
15

Show work please! I don't understand how to get this answer! I will give brainliest to the best answer!

Mathematics
1 answer:
Marina86 [1]3 years ago
4 0

Answer:

(x,y,z) = (2,-2,1)

Step-by-step explanation:

Three equations with three variables are given. Take two equations at a time to eliminate one variable.

                      x + y - z = -1                       .....(1)

                   4x -3y + 2z = 16                   .....(2)

                    2x - 2y - 3z = 5                   ......(3)

Solve (1) and (3) to eliminate z.

To do that multiply (1) by 2 and add (1) and (2). We get:

                        4x - 5z = 3                       ......(4)

Now, solve (2) and (3) and subtract them. We get:

                        2x + 13z = 17                    ......(5)

Solve (4) and (5). Multiply (5) by 2 and subtract. We get:

                                        z  = 1

Substituting z = 1, in (4) we get:  x = 2.

Now to find y, substitute values of x and y in (1).

⇒ x + y - z = -1 ⇒ 2 + y - 1 = -1

⇒ y = -2

∴ Values of (x, y, z) = (2, -2, 1).

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Step-by-step explanation:

ALGEBRA 1

Lilly S. asked • 08/16/17

3 girls get volunteer hours.

Katie, Elizabeth, and Siobhan voluenteer at the hospital. In a week, Katie volunteers 3 hours more than Elizabeth does and Siobhan volunteers 1 hour less than Elizabeth. Over 3 weeks, the number of hours Katie volunteers is equal to the sum of Elizabeth's and Siobhan's volunteer hours in 3 weeks.

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1 Expert Answer

By:

Best

Andy C. answered • 08/16/17

TUTOR 4.9 (27)

Math/Physics Tutor

SEE TUTORS LIKE THIS

We know nothing about Elizabeth hours, so that is where you assign the variable.

Elizabeth = X

Katie = X+3

Siobhan = X -1

Assuming this holds true over 3 weeks,

3(x+3) = 3X + 3(x-1)

3x + 9 = 3x + 3x - 3

3x + 9 = 6x - 3

0 = 6x - 3 - 3x - 9

0 = 3x - 12

12 = 3x

x=4

in one week:

Elizabeth volunteers 4 hours

Katie volunteers 7 hours

Siobhan volunteers 3 hours

over three weeks:

Elizabeth volunteers 12 hours

Katie volunteers 21 hours

Siobhan voluteers 9 hours

21 = 12 + 9, so yes it checks.

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