Question

what is the solution of the system of equations?
2x+2y+3z=-6
3x+5y+4z=3
2x+3y+4z=-10

Answer 1

lets try elimination method .
subtract 1st equation from 3rd equation, what u get ?

Answer 2

umm. well i know that the 2x cancel out right?

Answer 3

yes.

Answer 4

now what??

Answer 5

no, you had to subtract equations, not just remove 'x'.

Answer 6

2x+2y+3z=-6
- 2x+3y+4z=-10
_____________________
0x - 1y - 1z = 4
got this ?

Answer 7

yeah

Answer 8

know what do i do with 2nd equation

Answer 9

@hartnn

Answer 10

ok, so y+z=-4
now,
1)multiply 2nd equation with 2,
2)multiply 3rd equation with 3,
3) subtract those two resulting equations, what u get ?

Answer 11

yes, so u get
6x +10y +8z = 6

Answer 12

why am i doing that though

Answer 13

so , that you get 6x in both new equations, and when you subtract, 6x gets eliminated! :)

Answer 14

yes, correct, now subtract.

Answer 15

yes, so now you have 2 equations in terms of y and z
y+z=-4
y-4z =36
can you solve these ? its easy ...

Answer 16

to find, y and z.

Answer 17

how do i do that?

Answer 18

easy! subtract the equations and y gets eliminated!

Answer 19

@hartnn now what?

Answer 20

z=-8 is correct,
now put z=-8 in y+z=-4 and find y.

Answer 21

is this right

Answer 22

yes correct :)
now put y=4, z=-8 in any one of the original equations and find x !

Answer 23

@hartnn is this correct

Answer 24

good work! correct :)

Answer 25

thanks so much!!

Answer 26

welcome ^_^