Ok I have been trying to figure these 3 problems out and I know its probably something very simple as I can do other problems like them that are similar but these are racking my brain please help!

1. Write a system of equation where the solution is (-2,1)

2. This I need to find out x and y through elimination and/or substitution (same with #3):

4x+6y=18
6x+9y=18

3. 2/3x+y=-3
y-1/3x=6

Also, I can't seem to find the problem again but could someone give me insight on this one below as well? No one I have asked offline seems to know. :eek:

Probably can't get it completely right since I'm typing it by memory.

#4

Write the system of equation for this word problem:

Susie has $900 startup cash, each shirt she makes costs $20 to make. She plans on selling them for $30, how many shirts will it take for her to make a profit? (<--that is also part of the problem)

A) above question

B) write a system of equation showing the details of the word problem.

C) make a graph for the system of equation.


If anyone can help TY SO MUCH!

I'll answer the first one:

Starting with:
1x + 0y = -2
0x + 1y = +1.

Replace 1st equation with: Multiply 1st equation by 2 and add 2nd equation: 2x +1y = -3.

Replace 2nd equation with: Subtract 2nd equation from original 1st equation: 1x - 1y = -3.

So the new equations are:
2x +1y = -3
1x - 1y = -3.

Thanks a bunch! Anyone have insight on the others?

Quote:

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Originally Posted by xanus

Ok I have been trying to figure these 3 problems out and I know its probably something very simple as I can do other problems like them that are similar but these are racking my brain please help!

1. Write a system of equation where the solution is (-2,1)

2. This i need to find out x and y through elimination and/or substitution (same with #3):

4x+6y=18
6x+9y=18

3. 2/3x+y=-3
y-1/3x=6

Also, I can't seem to find the problem again but could someone give me insight on this one below as well? No one I have asked offline seems to know. :eek:

Probably can't get it completely right since im typing it by memory.

#4

Write the system of equation for this word problem:

Susie has $900 startup cash, each shirt she makes costs $20 to make. She plans on selling them for $30, how many shirts will it take for her to make a profit? (<--that is also part of the problem)

A) above question

B) write a system of equation showing the details of the word problem.

C) make a graph for the system of equation.


If anyone can help TY SO MUCH!

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how do I use elimanation to solve 3 system equations
x+y-z=2
2x+3y-6Z=5
-4x-5y+0.25z=-9