Question

Solve usingelimination method. If the ststem has not solution or an infinite number of solutions, state this -3x-8y=-88 and -3x-2y=-40

Answer 1

can someone please help me with this one

Answer 2

Solve using elimination method. If the system has no solution or an infinite number of solutions, state this:
-3x-8y=-88
-3x-2y=-40
Will someone help me with this one.
is this right -6x+10y=-48
-6x+10y-6=-48-6
10y=-48+-6
10y/10=-54/10
y=-54/10
then
6x-10y=-48
6x-10y-10=-48-10
6x=-48+-10
6x/6=-58/6
x=-58/6
will someone please tell me if this is right

Answer 3

infinite solutions, right?

Answer 4

Subtracting the second given equation from the first to eliminate x gives:
-6y = -48
y = 6
Sustituting the value just obtained for y in the second given equation we get:
3x -(2 * 8) = -40
3x - 16 = -40
3x = -24
x = -8

Answer 5

The solutions are x=y =8
You must have had some mis calculations above.

Answer 6

-3x-8y=-88
-3x-2y=-40

-3x-8y=-88
+3x+2y=40

-6y = - 48
y =8

replace to find x=8

Answer 7

Sorry. In the calculation of x I should have put -3x at the beginning and continued with the negative sign.
The value of x is found from:
-3x = -24
x = 8

Answer 8

x=y=8

Answer 9

ok so i am confused, can you rewrite the entire problem

Answer 10

-3x-8y=-88
gives
-3x=8y-88
put it in another equation ie -3x-2y=-40
we get y=8
and from this we get -3x=8(8)-88
-3x=-24
x=8

Answer 11

and so that it the answer= x=8 what about y

Answer 12

explain how you got this im confused

Answer 13

If you have time, this video and the ones after it walk you through how to do this
http://www.khanacademy.org/math/algebra/systems-of-eq-and-ineq/v/addition-elimination-method-1

Answer 14

But, to answer your question, if you manage to find x=8, you would find y by using one of the equations, say this one
-3x-8y=-88

replace x with 8:
-3*8-8y= -88
simplify: -24-8y= -88
add 8y to both sides
-24= 8y-88
add +88 to both sides
88-24= 8y
64= 8y
divide both sides by 8
8=y

Answer 15

k can you help me solve. Solve using the substitution method. show your work. If the system has no solution or an infinite number of solutions, state this. -7x+7y=-7 and x+9y=61

Answer 16

the substitution method
that means first solve for one of the variables. Pick
x+9y=61

can you solve for x (by "moving" 9y to the other side)?

Answer 17

i dont know can you

Answer 18

can you add -9y to both sides?

Answer 19

if you just will work this problem in full. i can figure it out from there. I am a person that learns by seeing

Answer 20

just narrate as you work the problem. thanks

Answer 21

x+9y=61
add -9y to both sides

Answer 22

is it x=52

Answer 23

you must not like letters. you have to keep -9y (can not combine with a number)
x= 61-9y

the y is important.

Answer 24

the whole problem is -7x+7y=-7 and
x+9y=61

Answer 25

so 52y

Answer 26

please just start from the beginning and writeout the whole solution to this problem. I am going to go to the site you gave me and evaluate what you gave me to better understand the whole thing

Answer 27

you have to remember a rule: if you have 2 numbers you can combine them example 1+2=3
if you have a letter and a number example 61 -9y you can not combine them.

Answer 28

so all we can do with
x+9y=61 is this
x+9y-9y= 61-9y

we can simplify 9y-9y (we have 9 y's and subtract away 9 y's) = 0
so
x= 61-9y

Your 2 equations are
-7x+7y=-7
x+9y=61 <-- this one we re-wrote as x= 61-9y

now let's look at the first equation. Can you divide
-7x + 7y = -7 by 7? (divide both sides (all terms)) by 7

Answer 29

yes

Answer 30

=0

Answer 31

no i mean =2

Answer 32

-7x + 7y = -7

divide each term by 7

Answer 33

do i divide each number or add 7x and 7y together first to get 14 then divide by 7 then -7/7

Answer 34

im sorry i am confused it would help me more to write the whole problem out and solution and solve and instruct each step all at once.

Answer 35

You divide each term by 7. pay attention! 7x+7y IS NOT 14 7+7=14

I'll do the first term: -7x / 7 = -x

Answer 36

ok

Answer 37

im sorry

Answer 38

-7x + 7y = -7

divide each term by 7

Answer 39

-x=-7 ? im sorry its been a long time for me

Answer 40

we want to divide each term by 7
-7x/7 + 7y/7 = -7/7

(If we do the same thing to each term, the equation remains true)
we get
-x + y = -1

now we use the 2nd equation (remember it?)
x= 61-9y

this equation says x is the same as (61-9y)
so replace the x in
-x + y = -1
with (61-9y)

Answer 41

is that it

Answer 42

the next step is replace x in
-x + y = -1
with (61-9y)

can you write down what we get?

Answer 43

hold on sorry had to go to rr

Answer 44

52y=-1?

Answer 45

don't do anything fancy. Just replace x with (61-9y) in
-x + y = -1

and post it

Answer 46

(61-9y)+y=-1

Answer 47

what happen to the minus sign in front?

Answer 48

52y+y=-1

Answer 49

(61-(-9y)+y=-1

Answer 50

you start with
-x + y = -1
now replace x with (61-9y)

-(61-9y) +y = -1

Do you see how to do that?

Answer 51

you got your work cut out with me, Huh? lol

Answer 52

why did you put the negative sign before the parenthesis

Answer 53

oh oh im sorry i see now

Answer 54

Now the minus sign is short hand for -1 times (stuff) . It is the same as
-1*(61-9y) + y = -1

The next step is "distribute the -1" That means multiply every term inside the parentheses by -1. Can you do that?

Answer 55

-61 and -9

Answer 56

-1*(61-9y) = -1*61 + -1*-9y
can you simplify (and stop ignoring the y)

Answer 57

-52y=-60-9y=
-52y=-51

Answer 58

y sorry

Answer 59

-52y=-51y

Answer 60

for practice, simplify this
-1*61 + -1*-9y

Answer 61

-61+-9y=-70

Answer 62

-61 is good
but -1*-9y is +9y ( minus times a minus becomes a plus)
it is not an equation (no = sign). we are just simplifying it. so
-1*61 + -1*-9y
is the same as
-61 + 9y

do you understand?

Answer 63

yes thanks

Answer 64

Ok, now back to the equation
-1*(61-9y) + y = -1
can you distribute the -1 ? Don't do too much. One step at a time.

Answer 65

-52+y=-1

Answer 66

-1(-52)+y=-1

Answer 67

"distribute the -1" That means multiply every term inside the parentheses by -1.
-1*(61-9y) = -1*61 + -1*-9y

try again