数学高手请进！

①975x0.25+9又3/4x76-9.75
=9.75*25+9.75*76-9.75
=9.75*(25+76-1)
=9.75*100
=975

②333387又1/2x79+790x66661又1/4
=333387又1/2x79+79x666612又1/2
=(333387又1/2+666612又1/2)*79
=1000000*79
=79000000

③1-1/6+1/42+1/56+1/72
=5/6+1/42+1/56+1/72
=35/42+1/42+1/56+1/72
=36/42+1/56+1/72
=6/7+1/56+1/72
=48/56+1/56+1/72
=49/56+1/72
=7/8+1/72
=63/72+1/72
=64/72

④(1+1/2+1/3+1/4)x(1/2+1/3+1/4+1/5)-(1+1/2+1/3+1/4+1/5)x(1/2+1/3+1/4)
=(1+1/2+1/3+1/4)x(1/2+1/3+1/4)+1/5*(1+1/2+1/3+1/4)-(1+1/2+1/3+1/4)*(1/2+1/3+1/4)- 1/5x(1/2+1/3+1/4)
=1/5*(1+1/2+1/3+1/4)-1/5x(1/2+1/3+1/4)
=1/5*1
=1/5

1、975x0.25+9又3/4x76-9.75
=9.75x1/4x100+9.75x76+9.75
=9.75x(1/4x100-1)+9.75x76
=9.75x24+9.75x76
=9.75x(24+76)
=9.75x100
=975
②333387又1/2x79+790x66661又1/4
=79x(333387又1/2+66661又1/4x10)
=79x(333387又1/2+66661又5/2)
=79x(333387又1/2+66663又1/2)
=79x400051
=
③1-1/6+1/42+1/56+1/72
=5/6+1/42+1/56+1/72
=35/42+1/42+1/56+1/72
=36/42+1/56+1/72
=6/7+1/56+1/72
=48/56+1/56+1/72
=49/56+1/72
=7/8+1/72
=63/72+1/72
=64/72
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