令3.15+2.17+5.61=x
令2.17+5.61=y
所以原式变成
x(y+6.6)-(x+6.6)y
=xy+6.6x-xy-6.6y
=6.6(x-y)
=6.6×[(3.15+2.17+5.61)-(2.17+5.61)]
=6.6×3.15
=20.79
（3.15+2.17+5.61）*（2.17+5.61+6.6）—（3.15+2.17+5.61+6.6）*（2.17+
3个回答
相关问题
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(3.15+2.17+5.61）×(2.17+5.61+6.6)-（3.15+2.17+
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口算：18÷9×5= 4.8+10.2= 6-2.5= 9.6-3.6= 17.9-4.5= 7.3+2.61= 50×
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用两种方法表达时间.5.45 6.15 6.45 5.15 2.17 2.33 5.17 5.33
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2.15-（5/6-1/12) 5/17-4/51+2/3
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1.32.8*91-16.4*92-1.75*656 2. 61*17分之1-1/17*47+20/17 3. （3.6
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(2.15﹢5.17＋3.62)×(5.17＋2.15＋8.5)－(3.62＋2.15＋8.5＋5.17)×(2.15＋
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（-6/5)*(-2/3)+(-6/5)*17/3= 要过程
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递等式计算：1.25*(0.4+2.8)*2.5;(3.61+6.39-6.39+3.61)/2
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75%x-2/3x=1/6 解方程 15*（1/15+2/17）*17 简便
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解方程 17x-25=17.5 5.2x+2.6x=46.8 3x+6.7=8.2．