Question

2x+3y = 17
2y + z = 1
5x +10z = 25

Find x

Answer 1

`x = 7`

Explanation:

From the equation
`2y + z = 1` , we can separate
`z` so that
`z = 1-2y`.

The equation
`5x+10z = 25` can then be turned into:

`5x+10(1-2y) = 25`

`5x+10-20y = 25`

`5x -20y = 15`

`x-4y = 3` (divide by
`5` on both sides)

We can now use elimination to solve for one of the variable:

`2(x-4y) = 2*3` (times 2 to get
`2x` for elimination)

`2x-8y=6`

`2x+3y-(2x-8y) = 17-6`

`11y = 11`

`y = 1`

Now, we can use substitution to solve for
`x`:

`2x+3y = 17`

`2x+3 = 17`

`x = 7`

Hope this helps :)

Answer 2

x = 7

Explanation:

Given the equations

2x + 3y = 17 → (1)

2y + z = 1 → (2)

5x + 10z = 25 → (3)

Rearrange (2) expressing z in terms of y

z = 1 - 2y

Substitute z = 1 - 2y into (3)

5x + 10(1 - 2y) = 25

5x + 10 - 20y = 25 ( subtract 10 from both sides )

5x - 20y = 15 → (4)

Multiply (1) by 20 and (4) by 3, then add to eliminate the y- term

40x + 60y = 340 → (5)

15x - 60y = 45 → (6)

Add (5) and (6) term by term to eliminate y, that is

55x = 385 ( divide both sides by 55 )

x = 7