x = 5
Step-by-step explanation:
Here we have the system of equations:
4x - 5y +7z= -14
9x + 2y +3z= 47
-y + x -5z = 11
We want to find the value of x.
To do it, we need to isolate one variable (not x) in one of the 3 equations. We could isolate y in the third equation to get:
x - 5z - 11 = y
now we can replace this in the other two equations to get:
4x - 5*( x - 5z - 11 ) +7z = -14
9x + 2*(x - 5z - 11 ) + 3z = 47
notice that now we have only two variables, now we need to simplify these two equations so we can get:
-x + 32z = -69
11x - 7z = 69
Now we do the same thing, this time we need to isolate z in one of the two equations, let's isolate it in the second one:
7z = 11x - 69
z = (11/7)*x - (69/7)
now we can replace this in the other equation to get:
-x + 32*( (11/7)*x - (69/7) ) = -69
now we have an equation for x, that we can solve to find its value:
-x + 32*(11/7)*x - 32*(69/7) = -69
x*(32*(11/7) - 1) = -69 + 32*(69/7)
x = [-69 + 32*(69/7)]/(32*(11/7) - 1) = 5
The value of x is 5.
