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Solve this linear equations: x + y + z = 34 1x + 10y + 5z = 100

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Answer

To solve this system of linear equations, we can use the method of substitution.

First, let's solve the first equation for x:

x = 34 - y - z

Now, we substitute this value of x into the second equation:

1(34 - y - z) + 10y + 5z = 100

34 - y - z + 10y + 5z = 100

34 + 9y + 4z = 100

Next, we simplify the second equation:

9y + 4z = 100 - 34

9y + 4z = 66

We can rewrite this equation as:

9y = 66 - 4z

y = (66 - 4z) / 9

Now, we substitute this value of y back into the first equation:

x + (66 - 4z) / 9 + z = 34

Multiplying through by 9 to eliminate the fraction:

9x + 66 - 4z + 9z = 306

9x + 5z = 240

Now we have a system of two equations in two variables:

9x + 5z = 240

9y + 4z = 66

We can solve this using the method of substitution or elimination. Let's use the method of elimination:

Multiplying the first equation by 4 and the second equation by 5, we get:

36x + 20z = 960

45y + 20z = 330

Subtracting the second equation from the first, we eliminate z:

36x - 45y = 630

We can simplify this equation by dividing through by 9:

4x - 5y = 70

Now, let's solve the new system of equations:

4x - 5y = 70

9y + 4z = 66

We can multiply the first equation by 9 and the second equation by 4 to eliminate x:

36x - 45y = 630

36y + 16z = 264

Now, subtracting the first equation from the second, we eliminate y:

36y + 16z - 36x + 45y = 264 - 630

81y + 16z = -366

Dividing through by 3, we get:

27y + 16z = -122

Now, we have a system of two equations in two variables:

4x - 5y = 70

27y + 16z = -122

We can solve this system using the method of substitution or elimination.

User Marco Merlini
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