Question 147891: When solving equations by graphing, I get confused if fractions are involved.
For example:
9x – 5y = 20 and
First equation
Let x = 0
-5y = 20
divide both sides by -5
y = -4
Let y = 0
9x = 20
Divide both sides by 9
X = 20/9 or 2 and 2/9
I would plot on a graph the two points
(0, -4)
(2 2/9, 0)
Second equation
5y – 9x = -20
Let x = 0
5y= -20
divide both sides by 5
y = -4
let y = 0
-9x = -20
Divide both sides by -9
x = -20/-9 or 20/9 or 2 2/9
I would plot on the graph the two pints
(0, -4) (2 2/9, 0)
Both equations are the same. Am I doing this correctly?
Thank you
Answer by Fombitz(32388)   (Show Source):
You can put this solution on YOUR website! Yes, you are doing it correctly.
Let's look at the equations to see why.
1.
2.
Re-arrange eq.2, x first then y,
2.
Now, multiply both sides of eq. 2 by (-1),
2.
You end up with eq. 1.
So yes, eq. 1 and eq. 2 are the same equation, as you already found out.
.
.
.
With regards to fractions, remember they're just numbers.
Maybe it's easier to change them to their approximate decimal values especially when graphing.
Instead of (2 2/9,0) maybe try (2.2,0).
It's usually close enough for graphing.
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