Asked by Sierra Elizabeth

What is the solution? use elimination .
4x-y=23
7x-y=21
PLEASE HELPPP!!!!
Answered by Steve
just subtract one from the other to eliminate y:

-3x = 2
Now you can get x, and then plug that in to get y.
Answered by Sierra Elizabeth
I don't understand?
Answered by Sierra Elizabeth
Where did you get -3x=2??
Answered by Steve
elimination means that you manipulate the equations so that one of the variables is eliminated.

Since the left sides are equal to the right sides, subtracting the left sides from each other and the right sides from each other gives a valid equation.

You can see that if you subtract -y from -y, the result is zero. 4x-7x = -3x, so you are left with

-3x + 0y = 2
Answered by Steve
clearly you need to review the material on elimination. Google will provide lots of examples.
Answered by Sierra Elizabeth
So what do we do to find the equation out ?
-3x+0y=2
the answer chosies they gave me are-
a.(11,0)
b.(4,-7)
c.(11,44)
d.(4,7)
Answered by Steve
clearly there is a typo in the equations, or the answer key is wrong. The equations you gave have solution

x = -2/3
y = -77/3

which you can check by plugging those values into both equations.

(4,-7) is a solution to 4x-y=23

It is also a solution to 7x+y = 21, not the equation you gave.

Be more careful with your postings.
Answered by Sierra Elizabeth
So the answer i got from that is (4,-7) correct??
Answered by Steve
So, with the correct equations, you'd have to add them to eliminate y:

4x-y=23
7x+y=21
-------------
11x=44
x=4

then plug that into either equation to figure out y.
Answered by Sierra Elizabeth
so, 7 and idk the other one ??
Answered by Sierra Elizabeth
so is it (11,44)??? @steve ??
Answered by Steve
NOOO

It's (4,-7)!

I explained how that pair fits both equations.

try plugging in your numbers and see that they are waaaaaayyyy off!
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