The given consists of of . Notice that the of
x in the first equation is the of the coefficient of
x in the second equation; they will add to be
0. Therefore, let's use the to find a solution to this system.
⎩⎪⎪⎨⎪⎪⎧x−3y+2z=11-x+4y+3z=52x−2y−4z=2(I)(II)(III)
We can start by adding the second equation to the first equation to eliminate the
x-terms.
⎩⎪⎪⎨⎪⎪⎧x−3y+2z=11-x+4y+3z=52x−2y−4z=2(I)(II)(III)
⎩⎪⎪⎨⎪⎪⎧x−3y+2z+(-x+4y+3z)=11+(5)-x+4y+3z=52x−2y−4z=2
⎩⎪⎪⎨⎪⎪⎧x−3y+2z−x+4y+3z=11+5-x+4y+3z=52x−2y−4z=2
⎩⎪⎪⎨⎪⎪⎧y+5z=16-x+4y+3z=52x−2y−4z=2
Having eliminated the
x-variable from the first equation, we can continue by creating additive inverse coefficients for
x in the second and third equations. Then, we can add or subtract these equations to eliminate
x from the second equation.
⎩⎪⎪⎨⎪⎪⎧y+5z=16-x+4y+3z=52x−2y−4z=2
⎩⎪⎪⎨⎪⎪⎧y+5z=16-2x+8y+6z=102x−2y−4z=2
⎩⎪⎪⎨⎪⎪⎧y+5z=16-2x+8y+6z+(2x−2y−4z)=10+(2)2x−2y−4z=2
⎩⎪⎪⎨⎪⎪⎧y+5z=16-2x+8y+6z+2x−2y−4z=10+22x−2y−4z=2
⎩⎪⎪⎨⎪⎪⎧y+5z=166y+2z=122x−2y−4z=2
⎩⎪⎪⎨⎪⎪⎧y+5z=163y+z=62x−2y−4z=2
Next, we will use our two equations that are only in terms of
y and
z to solve for the value of one of the variables. We will once again apply the Elimination Method, but this time it will be similar to when using it in a system with only two .
⎩⎪⎪⎨⎪⎪⎧y+5z=163y+z=62x−2y−4z=2
▼
(II): Solve by elimination
⎩⎪⎪⎨⎪⎪⎧y+5z=16-15y−5z=-302x−2y−4z=2
⎩⎪⎪⎨⎪⎪⎧y+5z=16-15y−5z+(y+5z)=-30+(16)2x−2y−4z=2
⎩⎪⎪⎨⎪⎪⎧y+5z=16-15y−5z+y+5z=-30+162x−2y−4z=2
⎩⎪⎪⎨⎪⎪⎧y+5z=16-14y=-142x−2y−4z=2
⎩⎪⎪⎨⎪⎪⎧y+5z=16y=12x−2y−4z=2
Now that we know that
y=1, we can substitute it into the first equation to find the value of
z.
⎩⎪⎪⎨⎪⎪⎧y+5z=16y=12x−2y−4z=2
⎩⎪⎪⎨⎪⎪⎧1+5z=16y=12x−2y−4z=2
⎩⎪⎪⎨⎪⎪⎧5z=15y=12x−2y−4z=2
⎩⎪⎪⎨⎪⎪⎧z=3y=12x−2y−4z=2
The value of
z is
3. Let's substitute both values into the third equation to find
x.
⎩⎪⎪⎨⎪⎪⎧z=3y=12x−2y−4z=2
⎩⎪⎪⎨⎪⎪⎧z=3y=12x−2(1)−4(3)=2
⎩⎪⎪⎨⎪⎪⎧z=3y=12x−2−12=2
⎩⎪⎪⎨⎪⎪⎧z=3y=12x−14=2
⎩⎪⎪⎨⎪⎪⎧z=3y=12x=16
⎩⎪⎪⎨⎪⎪⎧z=3y=1x=8
The solution to the system is
(8,1,3). This is the singular point at which all three planes .