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boyakko [2]
2 years ago
11

Solve the system of equations: X+y+z=5 -3x-4y+4z=15 2x-y-4z=-8

Mathematics
1 answer:
atroni [7]2 years ago
6 0

Answer:

  (x, y, z) = (3, -2, 4)

Step-by-step explanation:

The attachment shows a solution using a graphing calculator where the first equation is solved for z, and that expression is substituted into each of the other two equations. The solution to that system is (x, y) = (3, -2). Using these values in the expression for z, we find ...

  z = 5 -(3 +(-2)) = 4

The solution is (x, y, z) = (3, -2, 4).

__

Your graphing calculator and/or online tools can give you the reduced row echelon form of the augmented matrix representing the system:

  \left[\begin{array}{ccc|c}1&1&1&5\\-3&-4&4&15\\2&-1&-4&-8\end{array}\right]

__

If you're solving by hand, you can do the substitution described above to eliminate z from one equation. You can eliminate z from another equation by adding the last two:

  -3x -4y +4(5 -x -y) = 15   ⇒   -7x -8y = -5

  (-3x -4y +4z) +(2x -y -4z) = (15) +(-8)   ⇒   -x -5y = 7

This pair of equations can be solved for x and y in any of the usual ways. Using the second equation to substitute for x, for example, gives you ...

  -7(-5y -7) -8y = -5   ⇒   27y = -54   ⇒   y = -2

  x = -5(-2) -7 = 3

  z = 5 -(3) -(-2) = 4

_____

<em>Additional comment</em>

If all that is needed is a solution, we prefer a graphical or matrix approach. These take about the same amount of time. Both require a little additional effort to determine exact values when the solutions are not integers.

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3 years ago
How many solutions does the equation 5x+17=4(3x−1) have?
Stella [2.4K]

<u>Answer:</u>

one solution = 3

<u>Step-by-step explanation:</u>

Let's solve your equation step-by-step.

5x+17=4(3x−1)

Step 1: Simplify both sides of the equation.

5x+17=4(3x−1)

5x+17=(4)(3x)+(4)(−1)(Distribute)

5x+17=12x+−4

5x+17=12x−4

Step 2: Subtract 12x from both sides.

5x+17−12x=12x−4−12x

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Step 3: Subtract 17 from both sides.

−7x+17−17=−4−17

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Step 4: Divide both sides by -7

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4 0
2 years ago
James has eight coins in his pocket. All the coins are either dimes or quarters.The total value of the coins is $1.25. How many
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Answer:

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Step-by-step explanation:

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3 years ago
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