Question

need help!!!! solve the system by substitution
{ 2x-y+z=-4
{ z=5
{-2x+3y-z=-10

A. (-8,7,5)
B. (-8,-7,5)
C. (8,-7,5)
D. (-8,-7,-5)

Answer 1

start by substituting z=5 in first equation

Answer 2

so it would be 2x-y+5=-4
and the other one would be -2x+3y-2=-10

Answer 3

Perfect ! next, write them in two rows and add them vertically

Answer 4

*-5

Answer 5

2x-y+5=-4
2x+3y-5=-10

Answer 6

@ganeshie8 now what do you do ?

Answer 7

put z in 1st and 3rd equation after that add 1st and 3rd equation which will give you y put y and z in 1st equation then get x... (:

Answer 8

yeah i did that and i got 2x-y=-9
-2x+3y=-5
but i dont get how to solve that from there thats what im stuck on

Answer 9

write them two rows and add them vertically

2x-y = -9
-2x+3y = -5
------------------

Answer 10

okay does that mean 2x cancels out ?

Answer 11

yup

Answer 12

yes dear

Answer 13

and the equation would be 2y=-14 correct ?

Answer 14

y=-7

Answer 15

yep

Answer 16

Yes ! divide 2 both sides, and you will have y

Answer 17

okay so i got that which equation am i suppose to plug those into ?

Answer 18

any of 1st or 3rd

Answer 19

you have y & z values,
so u can find the remaining x value by pluggin it in any equation

Answer 20

pick one of below

2x-y = -9
-2x+3y = -5

cuz you just need to plug in y value to solve x

Answer 21

so the answer to the whole question would be B correct ? (-8,-7,5)

Answer 22

yes ! good job !!

Answer 23

thank you for helping me :)

Answer 24

np :)