(x﹣1)×(x+1)=x2﹣1
(x﹣1)×(x2+x+1)=x3﹣1
(x﹣1)×(x3+x2+x+1)=x4﹣1
…
由以上规律,我们可以猜测(x﹣1)×(xn+xn﹣1+…+x+1)=
67÷94= | 7﹣3.8= | 1÷12.5%= | 2.6+ = |
202= | 7a×6a= | 2.4×5= | = |
12÷12%= | 1.25×8= | 9.5﹣5= | 8.4﹣5.4×0= |
32﹣23= | 1﹣2÷7= | 8﹣0.4+0.6= | + ÷ + = |
1÷1%= 0.75×0.4= 10-0.86= +0.25=
125%×8= 1-1× = 1-56%= 18.84÷31.4=
24×( - )= - ×0= ( - )×3.5= =
199+ × = -1= 63.2÷6.9≈ 19×498≈
82= 1.2×1.4= 0.3×0.4×2.5= 1.5×105=
3²= 1+
2.5×4=
60÷6%= 0.1²+0.2²= 4÷ + ÷4=
估算:191020-9980≈ 万