Question

3.5×42-35×3.2+35用简便方法？

Answer 1

原式=3.5X4.2X10-3.5X10X3.2+3.5X10=3.5X(4.2X10-3.2X10+1X10)

=3.5X10X(4.2-3.2+1)=35X2=70

Answer 2

技巧：把第一项的3.5化为35，然后把每一项的35提出来
3.5×42-35×3.2+35
=35*4.2-35*3.2+35*1
=35*(4.2-3.2+1)
=35*2
=70

Answer 3

42＝4.2×10，35＝3.5×10，简便方法是：原式＝3.5×4.2×10－3.5×10×3.2+35＝35×4.2－35×3.2+35＝35×（4.2－3.2+1）＝35×2＝70

Answer 4

35×（4.2-3.2+1）=35×2=70

Answer 5

3.5×42-35×3.2+35
=35×4.2-35×3.2+35
=35×（4.2-3.2+1）
=35×2
=70