simlify by removing factors of 1

(r^2-1)/(r+1)square 2

r ^ 2 - 1 = ( r + 1 ) * ( r - 1 )

( r ^ 2 - 1 ) / ( r + 1 ) ^ 2 =

[ ( r + 1 ) * ( r - 1 ) ] / [ ( r + 1 ) * ( r + 1 ) ] =

( r - 1 ) / ( r + 1 )