Question

More Algebra

Answer 1

No clue how this one works

Answer 2

how you solve a system of equations with 3 unknowed terms x,y and z ?

Answer 3

Substitution or elimination?

Answer 4

exactly - nice

so but here in this case bc. there are a,b and c again in plus so i think will be more ussefuilly using substitution method

ok. ?

Answer 5

alright

Answer 6

do you know row echelon form? @HerpDerp

Answer 7

My teacher didn't want to teach us ._.

Answer 8

x +y +z = 2 => x = 2 -y - z so this result of x you substitute inside second and 3rd
ax +by +cz = 10 equation in place of x - like a first step
x -2y +z = 4

Answer 9

wait, this question is not about solving, its about finding the cases when the system has no solution, unique solution of infinitely many solutions

Answer 10

mhm

Answer 11

2a - ay - az + by + cz = 10
-3y=2, so y = \[\frac{ -2 }{ 3 }\]

Answer 12

So what's next O_O @jhonyy9

Answer 13

ok i understand it but first of all you need to solve this system to get the roots in function of a,b and c

Answer 14

There are answers in the back of the book, and it says to use elimination for e1 and e2, but I don't know how that works

Answer 15

look please subtract from the first equation the 3rd and will get

x +y +z = 2
x -2y +z = 4
--------------
0 3y 0 = -2

3y = -2

y = -2/3

yes ?

Answer 16

yeah i have that

Answer 17

I would say that augemented matrix is the easiest way, but you probably havent get to linear algebra yet

Answer 18

We can't use matrices on this question unfortunately :\

Answer 19

so now rewrite this system using this value of y

x -2/3 +z = 2
ax -2b/3 +cz = 10
x +4/3 +z = 4

do you can continue it now ?

Answer 20

x +z = 2+2/3
ax +cz = 10 +2b/3

Answer 21

using this value of z you can calculi the value of x

x +z = 2 + 2/3

x + [10 + (2b-8)/a] / (c-a) = 2 + 2/3

x = (2+ 2/3) - [10 + (2b-8)/a] / (c-a)

Answer 22

So i multiplied by -a, and I get
-ax - az = -8/3a

So then I add (eliminate) to get
-az +cz = 10 + 2/3b - 8a/3 , which is different from your answer

Answer 23

Ahhh I'm still really confused, sorry. I don't know how I can get a no solution with this.

Answer 24

why is it 2b/a

Answer 25

Have you tried to find "y" value?

Answer 26

y is -2/3

Answer 27

Have you tried to find x and z ?

Answer 28

uhhhh, sort of?

Answer 29

after you find "y", you can find x and z by plug "y" value to the original equation. Then use elimination to find x and z value

Answer 30

yes sorry this was my mistake there 2b/3 is correct

Answer 31

@Kevin exactly this was my above wrote way too

Answer 32

i get stuck with z = [10 + 2/3b - 8/3a] / (c-a)
and x = 8/3 - [10 + 2/3b - 8/3a] / (c-a)

Answer 33

But i dont know what to do form ther

Answer 34

now in function of a ,b and c you see that this system how many roots can have

Answer 35

@HerpDerp. That's exactly, This equation has infinitely solutions, because you can plug all kind of value for a or b or c to get 10

Answer 36

This question just same with your last question on http://openstudy.com/study#/updates/57d4cb46e4b0a5e834187332

Your first equation just like your third equation
I mean, it can be written as x + z = 8/3

So you just have 2 equations :
x + z = 8/ 3 and ax + by + cz = 10

Since there are more variables than equations, It can be have infinite solutions or zero solutions

Answer 37

The problem is asking something different