Question

x-6y-2z=-8
-x+5y+3z=2
3x -2y -4z=18

can you solve this using substitution method please i have my finale tom and i need to see how its done

Answer 1

please help i have like ten problems on my final for this and i totally forgot

Answer 2

Decide which variable you wish to substitute, x, y or z ?

Answer 3

i know the answers i just need to know how to do them

Answer 4

http://www.sosmath.com/soe/SE3/SE3.html
thats a tutorial about it.

Answer 5

I was going to walk you thru but I wanted you to be the decision maker on which variable you want to substitute.

Answer 6

um it doesnt matter x

Answer 7

I would suggest x, but that is just me, and you are you.

Answer 8

i picked x

Answer 9

Good choice. in the first equation x-6y-2z=-8. we need to isolate the x, in an expression that gives x in terms of y and z. Follow this sequence:
x-6y-2z=-8
x=6y + 2z - 8 That has isolated x and shows x =6y+2z-8
Now substitute this expression for x in the two lower equations.

Answer 10

how do you do the rest of it?

Answer 11

-6y-2z+8+5y+3z=2
-y+z=-6 This is result of substitution in the second equation, you do it in the thrid equation, while I eat my pizza.

Answer 12

Now substitute it in the third equation:
3(6y+2z-8)-2y-4z=18
18y+6z-24 -2y-4z=18
16y +2z=18+24
16y+2z=42

Answer 13

Here is what we have now:
x=6y+2z-8
-y+z=-6
16y+2z=42
Note the last two equation have only two unknowns (y and z) Take the -y+z=-6 and isolate the z getting z=y-6 and substitute this for z in the equation 16y + 2z=42. You would get 16y+2(y-6)=42
16y+2y-12=42
18y=54
y=3 Yeah! one down now substitute 3 for y in 16y + 2z = 42 getting
48 +2z =42
2z=-6
z=-3 (another one down), substitute for both y and z in x=6y+2z-8
x= 18-6-8=4
x=4

Answer 14

I kind of wanted to verify this:
x=4, z=-3, and y=3
x-6y-2z=-8
4-18+6=-8
-18+10=-8
-8=-8
Good enuff for me.