If you borrow $50 from your mom and $50 from your dad it makes $100. so the shirt you buy is $97. then you have $3 left. so you keep $1 and you give $1 to your mom and $1 to your dad. so now u owe them $49 each. $49 plus $49 is $98 plus then $1 you have it is $99. so where is the other $1.

In your pocket that is where the 1$ is

See below.

Step-by-step explanation:

That  is a bit bewildering!!  The only thing I can think of is you are adding  the quantities in the wrong way. From your standpoint your balance after you  borrowed the money was -$100  and you spent $97 leaving you with $3.  So you have to give back  $97 and $3, and -100 + 97 + 3 = 0.

Sorry guys it's actually
x^2 + 2x + 1
Because (x+1)(x+1) can be written either as x(x+1)+1(x+1) or (x+1)^2. (I'm sure there are other ways too but they're the ways I use!) Those ways show clearly when worked out that it's a 1 instead of a 2 as the constant! :)