Math Help - I need proof...

I need proof for the problem:
What are the values of x and y?
50x+100y=900
x+1.5y=15.5

The answer is x=8 and 5=y. I simply guessed and my teacher requires proof.
The proof cannot be a guess and check method.

Originally Posted by ceasar_19134

I need proof for the problem:
What are the values of x and y?
50x+100y=900
x+1.5y=15.5

The answer is x=8 and 5=y. I simply guessed and my teacher requires proof.

That is proof!
If it works that is your proof.

Originally Posted by ceasar_19134

I need proof for the problem:
What are the values of x and y?
50x+100y=900
x+1.5y=15.5

The answer is x=8 and 5=y. I simply guessed and my teacher requires proof.
The proof cannot be a guess and check method.

Multiply the second equation by 50 to get the pair of equations:

50x+100y=900
50x+75y=775

Now subtract to get:

25y=125.

And I expect you can take it from there.

RonL

Originally Posted by ThePerfectHacker

That is proof!
If it works that is your proof.

Sounds like a rather "Physics-y" proof if you ask me.

-Dan

Originally Posted by topsquark

Sounds like a rather "Physics-y" proof if you ask me.

-Dan

Why?

The reason why you use a technique or method to solve a problem is because you do not want to guess through uncountably many possibilities