Posted by **angel** on Tuesday, January 25, 2011 at 4:48pm.

3x+5y=0 2x-5y=-9

idk how 2 solve it then graph it my teacher eont help me plzz help

- algebra -
**helper**, Tuesday, January 25, 2011 at 5:02pm
I assume you need to solve these equations simultaneously ?

3x + 5y = 0

2x - 5y = -9

Solving by elimination method. The object is to eliminate one of the variables, either x or y.

Since you have +5y in the first equation and -5y in the second equation, you ADD the two equations.

This is because +5y + -5y = 0.

3x + 5y = 0

2x - 5y = -9

5x + 0 = -9

5x = -9

Divide both sides by 5

x = -9/5

To find y, substitute x = -9/5 in either equation and solve for y.

3x + 5y = 0

x = -9/5

3(-9/5) + 5y = 0

-27/5 + 5y = 0

Add 27/5 to both sides

-27/5 + 27/5 + 5y = 27/5

5y = 27/5

Divide both sides by 5

y = 27/5 /5

Multiplying the numerator by the reciprocal of the denominator is the same as dividing.

y = 27/5 * 1/5

y = 27/25

I'll leave the check to you.

x = -9/5, y = 27/5

- algebra -
**angel**, Tuesday, January 25, 2011 at 5:04pm
o ok ty

- algebra -
**helper**, Tuesday, January 25, 2011 at 5:34pm
You're welcome.

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