Question

Solve the following system of equations.

x + 4y + z = –10
3x – 3y + 6z = –21
x + 2y + 2z = –10
Answer
(–4, –1, –2)
(–3, –2, –3)
(1, –2, –3)
(2, –2, –4)

Answer 1

There are many ways of solving this.
a, Substitution
b, Elimination
c, Using a matrix.

Which one do you prefer, I can show it for you.

Answer 2

a

Answer 3

For that you have to express one of the equations in the form of x=somthing(no x in it)
Than you have to put this back to the other two equations.

Answer 4

from the first one we can see that x=-10-4y-z
Is it clear until this?

Answer 5

The second and third equations are:
3x – 3y + 6z = –21
x + 2y + 2z = –10

Now instead of x you write -10-4y-z

So it will be
3(-10-4y-z)-3y+6z=-21
-10-4y-z+2y+2z=-10

Clear?

Answer 6

my preferred method is cheating, but it will not help you on an exam

Answer 7

cheating? :) How?

Answer 8

http://www.wolframalpha.com/input/?i=x+%2B+4y+%2B+z+%3D+%E2%80%9310%2C3x+%E2%80%93+3y+%2B+6z+%3D+%E2%80%9321%2C+x+%2B+2y+%2B+2z+%3D+%E2%80%9310

Answer 9

got it with copy and paste and commas between the equations.