Algebra-Strat guide 1- 3rd edition-Pg 75-problem 13

[osaisai]

Hi, in Algebra-Strat guide 1- 3rd edition-Pg 75-problem 13:

can someone let me know why x^2+y^2 needs to be subtracted from both columns (A and B).

Thanks!

[tommywallach]

Hey There,

I have this on page 51, not page 13.

As for your question, this is a very important concept to understand when it comes to doing quantitative comparison. You can always add or subtract the same thing from both columns. Make sure you understand why; you're trying to figure out which column is bigger. Now imagine you had two columns with numbers in them:

Column A: 2
Column B: 3

Obviously, Column B is bigger. Do you see that if you add or subtract the same thing from both columns, column B will still be bigger?

Column A: 2 - x
Column B: 3 - x

It doesn't matter what x is (even if it's positive or negative). Column B will still be bigger.

So whenever you're manipulating the expressions in the two columns, if you see something that the two columns have in common, you should cancel it out through addition or subtraction, because it isn't actually affecting which column is bigger.

Let me know if that makes sense!

-t