A= 4/3+4/5+4/7+4/9+4/11+.....+4/99B=2/5+2/7+2/9+2/11+....+2/89C=1/3+1/4+1/5+1/6+.....+1/200D=5/4+5/8+5/12+5/16+5/20+....+5/400hết........................???
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