giúp mình hai bài này với
Tính nhanh
a) 1×5×6+2×10×12+4×20×24+9×45×54
1×3×5+2×6×10+4×12×20+9×27×47
b) 1992×19911991-1991×19921992
Tính nhanh:
a/ (1*5*6+2*10*12+4*20*24+9*45*54)/(1*3*5+2*6*10+4*12*20+9*27*45)
b/ [(1*5*6)+(2*10*12)+(4*20*24)+(9*45*54)]/[(1*3*5)+(2*6*10)+(4*12*20)+(9*27*45)]
/ là phân số nha!!!!!!!!!!!!!
Giá trị của biểu thức c=1*5*6+2*10*12+4*20*24+...+9*45*54/1*3*5+2*6*10+4*12*20+...+9*27*45 là c =
Tính nhanh : cho
A = 1 * 5 * 6 + 2 * 10 * 12 + 4 * 20 * 24 + 9 * 45 * 54
B = 1 * 3 * 5 + 2 * 6 * 10 + 4 * 12 * 20 + 9 * 27 * 45
Hãy tính A / B
tinh nhanh
a,A=100+98+96+...+2-97-95-...-1
b,B=1+2-3-4+5+6-7-8+9+10-11-12+...-229-330+301+302
c,C=41*66+34*41/3+7+11+...+79
d,D=1+2+3+...+200/6+8+10+...+34
e,E=1*5*6+2*10*12+20*24*4+9*45*54/1*3*5+2*6*10+4*12*20+9*27*45
Bai1 tính nhanh phép tính
a) 37581-9999
Bài2 tính nhanh
a) 36×28+36×82+64×69+64×41
b) A=41×66+34×41/3+7+11+...+79
c) 1×5×6+2×10×12+4×20×24+9×45×54/1×3×5+2×6×10+4×12×20+9×27×45
Bài 1 :
a) 37581 - 9999 = 37581 - 10000 - 1 = 27581 - 1 = 27580
k cho mình nha bạn !
a)37581-9999=37581-(9999+1-1)=37581-(10000+1)=37581-10000-1=27581+1=27582
Tính nhanh:
M=172-3-4+5+6-7-8+9+...+994-995-996+997+998
N=1992 x 19911991-1991 x 19921992
Tính nhẩm: 1) 373737 . 73 - 37 . 737373 2)19 . 41414141 - 41 . 19191919 3)123456 . 456789456789 - 456789 . 123456123456 4)250 . 12 . 7 5)24 . 125 . 9 6)125 . 44 . 18 7)8 . 24 . 6 + 12 . 4 . 52 + 2 . 22 . 24 8)18. 58 . 2 - 9 . 27 . 4 + 12 . 69 . 3 9)30 . 85 . 3 + 18 . 72 . 5 - 45 . 37 . 2 - 9 . 20 . 10
1) \(373737.73-37.737373\)
\(=37.10101.73-37.73.10101\)
\(=0\)
2) \(19.41414141-41.19191919\)
\(=19.41.1010101-41.19.1010101\)
\(=0\)
3) \(123456.456789456789-456789.123456123456\)
\(=123456.456789.1000001-456789.123456.1000001\)
\(=0\)
4) \(250.12.7\)
\(=250.4.3.7\)
\(=\left(250.4\right).\left(3.7\right)\)
\(=1000.21\)
\(=21000\)
5) \(24.125.9\)
\(=3.8.125.9\)
\(=\left(3.9\right).\left(8.125\right)\)
\(=27.1000\)
\(=27000\)
6) \(125.44.18\)
\(=125.4.11.2.9\)
\(=\left(125.4.2\right).\left(11.9\right)\)
\(=1000.99\)
\(=99000\)
7) \(8.24.6+12.4.52+2.22.24\)
\(=48.24+48.52+48.22\)
\(=48\left(24+52+22\right)\)
\(=48.98\)
\(=48\left(100-2\right)\)
\(=48.100-48.2\)
\(=4800-96\)
\(=4704\)
8) \(18.58.2-9.27.4+12.69.3\)
\(=36.58-36.27+36.69\)
\(=36\left(58-27+69\right)\)
\(=36.100=3600\)
9) \(30.85.3+18.72.5-45.37.2-9.20.10\)
\(=90.85+90.72-90.37-90.20\)
\(=90\left(85+72-37-20\right)\)
\(=90.100=9000\)
1)Tính nhanh:
M=172-3-4+5+6-7-8+9+...+994-995-996+997+998
N= 1992 . 19911991- 1991 . 19921992
2)Hãy vẽ 5 điểm phân biệt và kẻ các đường thẳng đi qua từng cặp hai trong 5 điểm ấy trong các trường hợp:
1. 1 đường thẳng
2. 5 đường thẳng
3. 8 đường thẳng
4. 10 đường thẳng
5. 6 đường thẳng
1) Tính nhanh:
M= 172-3-4+5+6-7-8+9+...+994-995-996+997+998
= 170+( 2-3-4+5)+ (6-7-8+9)+(10-11-12+13)+(14-15-16+17)+...(994-995-996+997)+998
= 170+(2+5-3-4)+(6+9-7-8)+(10+13-11-12)+(14+17-15-16)+...+(994+997-995-996)+998
= 170+(7-7)+(15-15)+(23-23)+(31-31)+...+(1991-1991)+998
= 170+0+0+0+0+...+0+998
= 170+998
= 1168
N= 1992 . 19911991 - 1991 . 19921992
= 1992 . 1991 . 10001 - 1991 . 1992 . 10001
= 1991 . 1992 . (10001 - 10001)
= 1991 . 1992 . 0
= 0
bài 1
4/7+4
3+6/11
3-5/7
21/9-2
15/24+2
63/45-20/25
3/4-2/8
6/7-5/8
37/45-5/9
46/39-11/13
5/12+3/4+1/3
1/2+3/7+11/14
7/10-(1/5+1/4)
15/4-2/3-3/4
`4/7+4`
`=4/7+4/1`
`=4/7+28/7`
`=32/7`
__
`3+6/11`
`=33/11+6/11`
`=39/11`
__
`3-5/7`
`=3/1-5/7`
`=21/7-5/7`
`=16/7`
__
`21/9-2`
`=21/9-18/9`
`=3/9`
`=1/3`
__
`15/24+2`
`=15/24+48/24`
`=63/24`
`=21/16`
__
`63/45-20/25`
`=63/45-4/5`
`=63/45-36/45`
`=27/45`
`=9/15`
__
`3/4-2/8`
`=3/4-1/4`
`=2/4`
__
`6/7-5/8`
`=48/56-35/56`
`=13/56`
__
`37/45-5/9`
`=37/45-25/45`
`=12/45`
`=4/15`
__
`46/39-11/13`
`=46/39-33/39`
`=13/39`
`=1/2`
__
`5/12+3/4+1/3`
`=5/12+9/12+4/12`
`=14/12+4/12`
`=18/12`
`=3/2`
__
`1/2+3/7+11/14`
`=7/14+6/14+11/14`
`=13/14+11/14`
`=24/14`
`=12/7`
__
`7/10-(1/5+1/4)`
`=7/10-(4/20+5/20)`
`=7/10-9/20`
`=14/20-9/20`
`=5/20`
`=1/4`
__
`15/4-2/3-3/4`
`=(15/4-3/4)-2/3`
`=12/4-2/3`
`=3-2/3`
`=9/3-2/3`
`=7/3`