tính nhanh
(145x99+145) - (143x101-143)
tính nhanh: b,6x1235x20-5x235x24
c,(145x99+145)-143x101-143
d,54x47-47x53-20-27
`#040911`
`b,`
`6 \times 1235 \times 20 - 5 \times 235 \times 24`
`= 6 \times (1000 + 235) \times 20 - 5 \times 235 \times 24`
`= 120 \times 1000 + 120 \times 235 - 120 \times 235`
`= 120 \times 1000 + 0`
`= 120000`
`c,`
\((145 \times 99+145)-143 \times 101-143\)
`=`\(145 \times 99 + 145 - 143 \times 101 - 143\)
`=`\(145 \times (99 + 1) - 143 \times (101 - 1)\)
`=`\(145 \times 100 - 143 \times 100\)
`=`\(100 \times (145 - 143)\)
`=`\(100 \times 2=200\)
`d,`
`54 \times 47 - 47 \times 53 - 20 - 27`
`= 54 \times 47 - 47 \times 53 - (20 + 27)`
`= 54 \times 47 - 47 \times 53 - 47`
`= 47 \times (54 - 53 - 1)`
`= 47 \times 0=0`
Tính bằng cách thuận tiện nhất: [145x99+145]-[143x101-143]
(145 x 99 + 145) - ( 143 x 101)
= (145 x (99+1) - (143 x (100+1))
=( 145x100 ) - (143 x 100 + 143 x 1)
= 14500 - ( 14300+143)
= 57
tinh bang cach thuan tien:
a,543 x46x54+54x543-14300
b.123x18x18x82+82x105
c.(145x99+145)-(143x101-143)
( 145x99+145)-(143x101)
làm hộ với
tính bằng cách thuận tiện !!
(145x99+145)-(143x101)
=(145x(99+1))-(143x(100+1))
=(145x100)-(143x100+143x1)
= 14500 -(14300+143)
= 14500-14443
= 57
k đi
=
tính nhanh:(532x7-266x14)x(143x101-143)
\(\text{(532.7-266.14).(143.101-143)}\)
\(\text{=(532.7-266.7.2).(143.101-143.1)}\)
\(\text{=(532.7-532.7).(143.100)}\)
\(\text{=0.(143.100)=0}\)
(532 x 7 - 266 x 14) x (143 x 101 - 143)
= (532 x 7 - 266 x 2 x 7) x [143 x (101 - 1)]
= (532 x 7 - 532 x 7) x 143 x 100
= 0 x 143 x 100
= 0
1.tính nhanh:
8x247x3+6x573x4 6x1235x20-5x235x24
(145x99+145)- (143x102-143) 54x47-47x53-20-27
a, 8 x 247 x 3 + 6 x 573 x 4
=24 x 247 + 24 x 573
=24 x ( 247 + 573 )
=24 x 820
=19680 ( mik nghĩ là bạn viết sai đề )
b, 6 x 1235 x 20 - 5 x 235 x 24
= 120 x 1235 - 120 x 235
= 120 x (1235 - 235)
=120 x 1000
=120000
c, ( 145 x 99 + 145 ) - ( 143 x 102 - 143 )
= [145 x ( 99+1)] - [ 143 x (102 - 1)]
= (145 x 100) - ( 143 x 100)
= (145 - 143) x 100
= 2 x 100
=200
d, 54 x 47 - 47 x 53 - 20 - 27
= 47 x (54 -53) - 20 - 27
= 47 x 1 - 20 - 27
= 47 - (20 + 27)
=47 - 47
=0
thật ra đề bài khó hơn nhưng tui cho dễ thôi
tính nhanh
a) 45+45+45+45+15+15+15+15=
b) 125+125+125+125-25-25-25-25=
c) (145x99+145) -( 143x102-143) =
d) 54x47-47x53-20-27=
e)326x728+327x272=
a.45+45+45+45+15+15+15+15=45×4+15×4=4×(45+15)=4×60=240
125+125+125+125-25-25-25-25=125×4-25×4=4×(125-25)=4×100=400
(145x99+145)-(143x102-143)
làm rõ ra và làm thuận tiện nhất nữa nha
(145x99+145)-(143x102-143)
=145x100-143x101
=14500-14443
=57
\(\left(145x99+145\right)-\left(143x102-143\right)\)
\(=145x100-143x101\)
\(=14500-14443\)
\(=57\)