(25×39+25×61)×4,(75×99+75)×4能巧算吗?如果能,怎么巧算
来源:学生作业帮助网 编辑:作业帮 时间:2024/06/27 02:43:47
![(25×39+25×61)×4,(75×99+75)×4能巧算吗?如果能,怎么巧算](/uploads/image/z/104947-43-7.jpg?t=%2825%C3%9739%EF%BC%8B25%C3%9761%29%C3%974%2C%2875%C3%9799%EF%BC%8B75%29%C3%974%E8%83%BD%E5%B7%A7%E7%AE%97%E5%90%97%3F%E5%A6%82%E6%9E%9C%E8%83%BD%2C%E6%80%8E%E4%B9%88%E5%B7%A7%E7%AE%97)
(25×39+25×61)×4,(75×99+75)×4能巧算吗?如果能,怎么巧算
(25×39+25×61)×4,(75×99+75)×4能巧算吗?如果能,怎么巧算
(25×39+25×61)×4,(75×99+75)×4能巧算吗?如果能,怎么巧算
(25×39+25×61)×4=[25x(39+61)]x4=(39+61)x(25x4)=10000
,(75×99+75)×4=[75x(99+1)]x4=(99+1)x75x4=30000
25*39+25*61=25(39+61)=25*100 所以原式为(25*(39+61))*4=25*100*4=10000
75*99+75=75*(99+1)=75*100=25*3*100 所以可写为25*3*100*4=30000
(25×39+25×61)×4
=25×(39+61)×4
=100×100
=10000
(75×99+75)×4
=75×(99+1)×4
=25×4×3×100
=100×300
=30000
(25×39+25×61)×4 = (25×(39 + 61) ) × 4 = 25 × 100 × 4 = 10000
(75×99+75)×4 = 75 × (99 + 1) × 4 = 75 × 100 × 4 = 3 × 25 × 4 × 100 = 30000
(25×39+25×61)×4
=25×(39+61)×4
=(25×4)×(39+61)
=100×100
=10000
(75×99+75)×4
=75×(99+1)×4
=(25×4)×(99+1)×3
=100×100×3
=30000
抽取公因式后,原式=25×(39+61)×4×75(99+1)=25×100×4×75×100=75000000