Question

t=2r+3
5r-4t=6
I need to solve the system by substitution and check my answer, please help :(((

Answer 1

5r-4t=6

5r-4(2r+3)=6 ... replace t with 2r+3 (since t = 2r+3)

5r - 8r - 12 = 6

solve for r and tell me what you get

Answer 2

working on it now

Answer 3

ok

Answer 4

r=-6

Answer 5

good

Answer 6

now use that to find t

Answer 7

now i replace it in the equation and solve for t ?

Answer 8

t=-9?

Answer 9

perfect

r = -6
t = -9

Answer 10

can you keep helping me with the rest ?

Answer 11

r+s=-12
4r-6s=12

Answer 12

how much more do you have?

Answer 13

12 more

Answer 14

as long as you can help me with like six

Answer 15

just like you did on the first one

Answer 16

please :((((((((((

Answer 17

12 is quite a lot, but 6 sounds more manageable

Answer 18

okay

Answer 19

we'll see how it goes, but I'm not doing all 12

Answer 20

ok

Answer 21

r+s=-12
4r-6s=12
solve by substitution

Answer 22

solve the first equation for r

r+s=-12

r = -12 - s

then plug this into the second equation

4r-6s=12

4(-12 - s) - 6s = 12

-48 - 4s - 6s = 12

solve for s

Answer 23

i did that one all by myself :) i didnt even look at the screen but now its elimination :(

Answer 24

x+y=12
x-y=2
solve by elimination

Answer 25

add the two equations to get

x+y=12
x-y=2
--------
2x+0y=14


so 2x = 14 -----> x = ??

Answer 26

notice how the y terms cancel if and only if the y coefficients are equal and opposite

Answer 27

7 :-))))))))))))

Answer 28

YOU ARE AWESOME

Answer 29

lol thx

Answer 30

yes x = 7, then use this with any original equation to find y

Answer 31

y=5 :)

Answer 32

good

Answer 33

i just did one by myself, im going to continue until i need you but dont forget about me

Answer 34

ok that's great you're doing it on your own

I'm sure you'll be fine

Answer 35

and you can always ask questions here

Answer 36

okay wait i did this one and w gave me -2 but i dont think thats correct

Answer 37

2w+5y=-24
3w-5y=14
and im solving for elimination

Answer 38

w = -2 is correct

Answer 39

you got to trust yourself more

Answer 40

i got rid of the 5 y's
added the w's, it gave me 5w and then added the -24 +14 and it gave me -10

Answer 41

yep 5w = -10 ----> w = -2

Answer 42

ok thanks just making sure

Answer 43

and y=5, correct?

Answer 44

it doesnt fit in....

Answer 45

no y = 5 is incorrect

Answer 46

help please?

Answer 47

2w+5y=-24

2(-2)+5y=-24

-4 + 5y = -24

5y = -24 + 4

5y = -20

y = -20/5

y = -4

Answer 48

you could use the other equation too, either way you will get y = -4

Answer 49

okay i need help with this one

Answer 50

9a-3d=3
-3a+d=-1
solve by elimination

Answer 51

do i have to multiply 3 to all of the parts in the second equation?

Answer 52

yes you do, then add the equations

Answer 53

cant be solved because ts dependent

Answer 54

so are there no solutions? or infinitely many?

Answer 55

no solutions....

Answer 56

i mean it will always be 0

Answer 57

if you multiply everything in equation 2 by 3, you get -9a+3d = -3

then add this to the first equation to get

9a-3d=3
-9a+3d=-3
------------
0a+0d=0

so we get 0 = 0

Answer 58

0 = 0 is always true no matter what

so that means you can pick any number you want for 'a' and you'll have a solution (note: d will depend on 'a')

therefore there are infinitely many solutions because of that fact

Answer 59

what does it mean when a system is inconsistant

Answer 60

when there are no solutions (so the two lines are parallel and never intersect)

Answer 61

6x-2y=11
-9+3y=16

Answer 62

is there an x in the second equation?

Answer 63

6x-2y=11
-9x+3y+16

Answer 64

my bad

Answer 65

..

Answer 66

ok which method do you want to use

Answer 67

elimination

Answer 68

i think it is inconsistant cause i couldent get anything

Answer 69

I don't think it's inconsistent

Answer 70

hmm let me check

Answer 71

ok yes it is inconsistent

Answer 72

y=4-x
3x+y=6
solve by elimination

Answer 73

im stuck, please help

Answer 74

y=4-x

y+x=4-x+x

x+y = 4

Answer 75

so we have this system


x+y = 4
3x+y = 6

Answer 76

then i multipied x times -3 and i was super confused

Answer 77

help

Answer 78

why not multiply either equation by -1 then add (this will eliminate the y terms)

Answer 79

i got
-1x-1y=-4
3x+y=-6

Answer 80

now add the two equations

Answer 81

got it

Answer 82

your my new favorite teacher

Answer 83

thanks, I'm flattered