Question

Use substitution to find the solutions (if any).
3x + 7y = 3 and 12x + 28y = 16

Answer 1

u know how 2 do substitution?

Answer 2

they are parallel lines, they wont meet. so there wont be any solution

Answer 3

still learning

Answer 4

many solutions

Answer 5

i need to show my work

Answer 6

Okay- the goal of substitution is to get one equation with one variable.

First, you put one of the equations in terms of one of the variables.

i.e, if your equation was a+b=7, and u wanted 2 put it in terms of a, it would become a=7-b

Answer 7

vijay, u r incorrect.

Answer 8

Then, you'd put 7-b everywhere you saw a in the second equation. That's substitution

Answer 9

SO for this problem, get an equation in terms of y or x. lets do x, caus x's are cool.

Answer 10

this is the answer I got for the first 1 x = 1 + -2.333333333y

Answer 11

3x+7y=3
3x=3-7y
x=1-(7/3y)

Answer 12

I'd leave it in fractional form, caus it looks a lot nicer that way.

Answer 13

ok

Answer 14

so plug 1-(7/3 y) wherever u c x in the second equation
I'd use parenthesis in case u have 2 distribute
(1-(7-3 y))

Answer 15

sry! meant 7/3!

Answer 16

3((1-(7/3y))+2y/3=8 right?

Answer 17

hold on-

Answer 18

Not quite sure what u did. u started with 12(1-(7/3 y))+28y=16, right?

Answer 19

sorry wrong prob...lol

Answer 20

for me not you

Answer 21

no hugie!

Answer 22

i have been doing this for 10 hours I am brain dead

Answer 23

THAT stinks :(. Pull through and I'll give u a medal!

Answer 24

this is where I have the problem is on the second equation

Answer 25

ok
So we have 12(1-(7/3 y))+28y=16,right?
I'd divide the whole equation by 4 to simplify it. just means u have
3(1-(7/3 y))+7y=4

Answer 26

ok

Answer 27

And then distribute the negative sign
3(1(-7/3 y))+7y=4

Answer 28

distribute the 1 (doesn't change anything), and then the 3.
-7y+7y=4

Answer 29

you lost me there

Answer 30

which step?

Answer 31

distribute one

Answer 32

okay. u know how 2 distribute, right?

Answer 33

no

Answer 34

show me what you mean..can yu write it out

Answer 35

Okay then. THere's something called Distributive Property in math. It just means multiplying a number through a pair of parenthesis.

3(x-1)
Distribute the 3
3x-3

multiply the 3 by everything in the parenthesis
3*x=3x
3*-1=-3
3x-3

Answer 36

geddit or want me to show u another one?

Answer 37

no i think i got it

Answer 38

so my answer is 4

Answer 39

no.
3(1-(7/3 y)+7y=4
first distribute the negative sign through
cool math fact- negative signs can be rewritten as -1 times the number being minus-ed
-3=-1*3
that means multiply every term in the parenthesis by a negative one

Answer 40

so i get 3x.666666667=7y=4?

Answer 41

i ment +

Answer 42

Not done yet
3(1(-7/3 y) +7y=4
Now distribute the 1
but anything multiplied by a positive one stays the same number
ex. 6*1=6
so now we have 3(-7/3 y)+7y=4

Answer 43

Distribute the 3, and your denominator is no more
-7*3
----- 3's cancel out.
3

Answer 44

Now u have -7y+7y=4

Answer 45

so 3*-7+7y=4?

Answer 46

oh ok

Answer 47

so now we have y=4

Answer 48

No, not quite. now we have
-7y+7y=4
7y-7y=4
0=4
it doesn't work- there's no solution
All that work for nothing! (literally)

Answer 49

ok now I have to A. For equation ___________
1. The x-intercept is ___.
2. The y-intercept is ___.
3. The slope is ___.

B. For equation ___________
1. The x-intercept is ___.
2. The y-intercept is ___.
3. The slope is ___.

Answer 50

can you help with this?

Answer 51

Get each equation into y=mx+b form
u know what that is?

Answer 52

yes

Answer 53

ok. Put each equation into that form and post them

Answer 54

i am so tired I cant figure it out. I will just stop here and turn this in like it is.

Answer 55

COme on, ur so close!

Answer 56

do the first one...that will be a hint for me

Answer 57

Hm- How about I do the second and u do the first? (leave the slope in fractional form)

Answer 58

ok

Answer 59

second equation
y=-3/7 x +2/7
what's the first?

Answer 60

y= i dont know

Answer 61

first equation
y=-3/7x+3

Answer 62

First equation
slope: -3/7 x
y intercept: 3
x intercept:7

Answer 63

you have no idea how much I appreciate all your help

Answer 64

i got 11 out of 55 on my last paper

Answer 65

Second equation
slope: -3/7
y intercept: 2/7
x intercept:-2/3

drop the x for the first slope

Answer 66

good luck. Only gave u the answers b/c u seemed desperate

Answer 67

I have 3 word problems left then I can quit

Answer 68

trust me at this point i am

Answer 69

thanks so much!!!!!!! for all your help

Answer 70

welcome g
ot 2 get off