Question

Use substitution to solve the following systems of equations 9x+4y=2
2x+y=1

Answer 1

Great okay.. can you do something for me - just multiply every term of both the LHS and the RHS of the second equation by 4? What do you get?

Answer 2

LHS RHS? whats that

Answer 3

use \(\small \textbf{*substitution*}\) gotta love that word hehe

Answer 4

x = -2, y = 5 GOGOGO :P

Answer 5

lhs = left hand side
rhs = right hand side

Answer 6

how do you get that though i want to understand

Answer 7

look at your equations:

1) 9x + 4y = 2
2) 2x + y = 1

which one has no coefficient?

Answer 8

the second one

Answer 9

which one in the second?

Answer 10

y

Answer 11

right. so isolate y

Answer 12

what do you get if you isolate y in

2x + y = 1

Answer 13

1?

Answer 14

what happened to 2x?

Answer 15

so its 2x+-2??

Answer 16

idk to be honest im lost

Answer 17

no..

Answer 18

look at 2x + y = 1

what will you do so that only y is on the left side?

Answer 19

subtract 2 from 2x?

Answer 20

nope... let's try this
3 + y = 1

what will you do to isolate y?

Answer 21

we subtract 3 from both sides?

Answer 22

correct

Answer 23

so how do you isolate y in

2x + y = 1

Answer 24

we subtract 2x from both sides

Answer 25

right..what does that give you

Answer 26

so it will give me y=-1

Answer 27

no you subtracted 2x from BOTH SIDES right?

Answer 28

yea 2x+y=1
-2
cancels out

Answer 29

2x - 2 does not cancel out

Answer 30

its gives u -4

Answer 31

no.. you cant combine 2x and 2

Answer 32

remember what you said earlier..we subtract 2x from both sides...not 2

Answer 33

2x+y=1
-2x -2x

Answer 34

so then it cancels out

Answer 35

hep

Answer 36

-2x and 2x cancel on the left side, but what makes you think -2x cancels with anything on the right side?

Answer 37

no im saying it cancels out on that side

Answer 38

which side?

Answer 39

on the left

Answer 40

then its 1-2x right which equals

Answer 41

which equal what...?

Answer 42

-1

Answer 43

why is it equal to -1 ???
no...
what you have for the RHS is correct

but on the left, what is left after the 2x and the -2x cancel?

Answer 44

y=-1

Answer 45

ugh this sucks

Answer 46

you need to think of each side separately