A=19,98x 1999,8=[19,97+0,01]x1999,8=19,97x1999,8+0,01x199,8=19.97x1999.8+1,998
B=19,97x 199,9=19,97x[199.8+0,1]=19.97x199.8+0.1x19.97=19.97x199.8+1.997
Vì 19.97x1999.8=19.97x1999.8
Mà 1,998>1,997
Nên 19.97x1999.8+1,998>19.97x1999.8+1,997
Vậy A>B
A=1/3=1/3
B=33,3x33,4+0,2 / 33,5x33,3+0,3=33,3x33,4+0,2/[33.4+0.1]x33.3+0.3=33,3x33,4+0,2/33.3x33.4+33.3x0.1+0.3
=33.3x33.4+0.2/33.3x33.4+3.33+0.3
=33.3x33.4+0.2/33.3x33.4+3.63