Question

how to solve these:

1. 2x+y-z=2
x+2y+4z=1
5x+y-7z=4

2. 3/x + 4/y + 6/z = 1
9/x + 8/y - 12/z = 3
9/x - 4/y + 12/z = 4

3. x+y+z=0
y+z-2w=-5
2x-y+3w=9
x+3z-w=-1

4. 2x-y+z-w =5
2y-z+2w=-4
x+y-3w=0
3y+2z-2w=1

by elimination and substitution..
help me please ..

Answer 1

This is a nightmare :3

Answer 2

I reckon the first is the easiest, so let's get down to business...

Answer 3

Oh my.

Answer 4

FUN!!!!1!!!!

Answer 5

I shudder at what you find fun.
Now, as for the first set of equations, the most straightforward way to go about this is substitution...

Answer 6

huhu T_T .. hate it ..

Answer 7

Let's look at the first equation of the first system...
2x + y - z = 2

Answer 8

From here, it follows that 2x + y - 2 = z
correct?

Answer 9

yes? haha .. not sure. hm, ah! yeah.. correct!

Answer 10

I don't like 'not sure'.
Be sure, or clarify with me.

Answer 11

What didn't you get?

Answer 12

Someday, but not today.

Answer 13

ahh.. i know na . :) next?

Answer 14

z = 2x + y - 2

Now, in the other two equations
x + 2y + 4z = 1
5x + y - 7z = 4

Answer 15

I want you to replace z with that new expression. Tell me what you get.

Answer 16

x + 2y + 4 (2x+y-z) = 1
5x + y - 7 (2x+y-z) =4

right?

Answer 17

No.

Answer 18

ee how?

Answer 19

\[\huge \color{red}{z= 2x + y - \boxed2}\]

Answer 20

ahh.. i know na ..
x + 2y + 4 (2x+y-2) = 1
5x + y - 7 (2x+y-2) =4

right?

Answer 21

Now, simplify.

Answer 22

x + 2y + 8x + 4y - 8 = 1
5x + y - 14x - 7y + 14 = 4

Answer 23

...now combine like terms

Answer 24

wouldn't elimination be easier on the 1st one

Answer 25

And out of nowhere,a pretty @texaschic101 appears.

Answer 26

I don't know which is easier.

Answer 27

9x + 6y = 9
-9x - 6y = -10

Answer 28

lol...hello primeralph