Two equations are given below:
a − 3b = 4
a = b − 2
What is the solution to the set of equations in the form (a, b)?
(−2, −2)
(−3, −1)
(−9, −7)
(−5, −3)

- anonymous

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- anonymous

please help

- anonymous

can anyone help?

- anonymous

since you know what a is equal to plug its value into the first equation so that you have the first equation only in terms of b, then solve for b

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## More answers

- anonymous

@AliSurfCat ok?

- anonymous

I really dont know

- anonymous

what is a equal to? according to the second equation

- anonymous

thats the thing I dont know:(

- anonymous

if i show you this, z = 10, what is z equal to?

- anonymous

10

- anonymous

perfect, now if i show you this, a = b − 2, what is a equal to?

- anonymous

a equals 4

- anonymous

a equals b - 2

- anonymous

and be equals 6

- anonymous

no, a equals b - 2

- anonymous

okay

- anonymous

ok lets make sure you understand this, if i show you j = 5i +z - 2, what is j equal to?

- anonymous

5i +z - 2

- anonymous

perfect :)

- anonymous

ok back to your question, so we know a is equal to b - 2

- anonymous

since a is equal to b -2 can you please replace a in the first equation with b -2 since they equal the same thing

- anonymous

ok, b-2 − 3b = 4

- anonymous

perfect :)

- anonymous

now can you solve for b? with that equation b -2 -3b = 4

- anonymous

cna you help me on this one?

- anonymous

sure

- anonymous

to solve for b we need to find out what b equals, so we have an equation that has only numbers and the variable b, so we need to perform some arithmetic on the equation to get b by itself on one side of the equals sign

- anonymous

so lets start by only getting terms with a b in them on one side,
so if you have b - 2 - 3b = 4, what would be a good step to take so that there are only terms with b in them on the left side?

- anonymous

how can i get rid of the -2 on the left side?

- anonymous

ok

- anonymous

what happens if we add 2 on both sides of the equation, what do you get?

- anonymous

you get 6

- anonymous

i get 6 on the right hand side of the equals sign but what about on the left side?

- anonymous

b - 2 + 2 - 3b = 4 + 2
b - 2 + 2 - 3b = 6

- anonymous

hey I have a few minutes left to turn this in please help

- anonymous

i am helping, if you just want the answer, i cant do that

- anonymous

I dont but think it is A

- anonymous

good luck bud

- anonymous

ok well thanks

- anonymous

if you change your mind and want to keep working through it let me know

- anonymous

I do :)

- anonymous

ok so we added 2 to both sides to get this
b - 2 + 2 - 3b = 4 + 2
b - 2 + 2 - 3b = 6
can you simplify this and tell me what we get?

- anonymous

b-4-3b=6

- anonymous

close, but
-2 + 2 is not equal to -4

- anonymous

ohhh sorry got a little confused

- anonymous

ok so -2 + 2 = what?

- anonymous

it eaquals 0

- anonymous

perfect,
now we have
b + 0 - 3b=6
which equals
b - 3b = 6

- anonymous

can you simplify b - 3b = 6 by combining the b terms?

- anonymous

how do I do that

- anonymous

if i have 1b and i take away 3b's how many b's do i have?

- anonymous

do I just do 3b=6???

- anonymous

1b - 3b

- anonymous

--2b

- anonymous

correct

- anonymous

so we are almost done
we have
-2b = 6, now how can you get b by itself?

- anonymous

how can we get rid of the -2?

- anonymous

turn it into a 1

- anonymous

by adding 2 on both sides

- anonymous

by dividing both sides by -2

- anonymous

yes thats what I meant lol

- anonymous

-2/-2 = 1
so
(-2b)/-2 = 6/(-2)
1b = 6/(-2)
b = 6 / (-2)

- anonymous

so what is 6 / (-2),
6 divided by -2

- anonymous

-3

- anonymous

perfect, so b = -3, so now you know the answer, do you see an answer where the second number is -3?
(a, b)
(a, -3)

- anonymous

which one is it?

- anonymous

we can find a very easily also
looking at the second equation we have a = b - 2
so if i plug in b i get
a = -3 -2

- anonymous

so it is D?

- anonymous

correct :)

- anonymous

yay thanks so much

- anonymous

you're welcome, please do some practice on this stuff or your future classes in college will be very difficult, visit khan academy and get help on here and other sites also

- anonymous

I do

- anonymous

good :)

- anonymous

have a good day

- anonymous

you too

- TheViper

nice to see too much long conversation in such a simple question

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