①8(2x+2.6)=32
②1.25×3.2×2.5
③4.6×2.89+6.11×4.6+4.6
④1995×1995+1994×1994-1995×1994-1994×1993.
人气:493 ℃ 时间:2020-03-26 10:02:14
解答
①8(2x+2.6)=32,
8(2x+2.6)÷8=32÷8,
2x+2.6=4,
2x+2.6-2.6=4-2.6,
2x=1.4,
2x÷2=1.4÷2,
x=0.7;
②1.25×3.2×2.5,
=1.25×(0.8×4)×2.5,
=(1.25×0.8)×(4×2.5),
=1×10,
=10;
③4.6×2.89+6.11×4.6+4.6,
=4.6×(2.89+6.11+1),
=4.6×10,
=46;
④1995×1995+1994×1994-1995×1994-1994×1993,
=1995×1995-1995×1994+1994×1994-1994×1993,
=1995×(1995-1994)+1994×(1994-1993),
=1995×1+1994×1,
=1995+1994,
=3989.
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