# Solve systems by substitution

• Apr 4th 2007, 07:30 PM
Patience
Solve systems by substitution
These substitution equation is really frustrating me what is the purpose of these equation I don't see how they are part of every day life.
Anyway any help on this equation is very helpful.

8x – 4y = 16
y = 2x – 4
• Apr 4th 2007, 07:32 PM
ThePerfectHacker
Quote:

Originally Posted by Patience
These substitution equation is really frustrating me what is the purpose of these equation I don't see how they are part of every day life.

Stop complaining. You should see the math I do. I purposely choose it so that I can have no meaning in real life. Think of it as abstract expressionism.
Quote:

Anyway any help on this equation is very helpful.

8x – 4y = 16
y = 2x – 4
8x-4y=16
y=2x-4

Thus,

8x-4(2x-4)=16

8x-8x+16=16

16=16

Which is true.

That means there were infinitely many solutions to that equation.

Thus, if x=t (some number) then the second equation tells us that,
y=2t-4.

Thus,

x=t
y=2t-4.

For any number t.