Tính nhanh
a) 1.2.3...9 - 1.2.3...8 - 1.2.3...7.82
b) 1-2-3+4+5-6-7+8+9-10-11+12+13
Bài 2
Chứng minh A=2+22+23+24+...+260 chia hết cho 7
Ai biết giúp mình với
Bài 1 Tính nhanh
1.2.3...9-1.2.3...8-1.2.3...7.8.8
1152-(374+1152)+(-65+374)
13-12+11+10-9+8-7-6+5-4+3+2-1
Tính hợp lý:
a. (102+112+122) : (132+142)
b. 1.2.3...9-1.2.3...8-1.2.3...7.82
c. 13-12+11+10-9+8-7-6+5-4+3+2-1
\(b)\) \(1.2.3...9-1.2.3...8-1.2.3...8^2\)
\(=\)\(1.2.3...8\left(9-1-8\right)\)
\(=\)\(1.2.3...8\left(9-9\right)\)
\(=\)\(1.2.3...8.0\)
\(=\)\(0\)
1) 1.2.3...9 - 1.2.3...8 - 1.2.3...7.82
2) \(\frac{\left(3.4.2^{16}\right)^2}{11.2^{13}.4^{11}-16^9}\)
3)13 - 12 + 11 + 10 - 9 + 8 - 7 - 6 + 5 -4 +3 +2 -1
Câu 1 dễ mà :
1.2.3...9 - 1.2.3...8 - 1.2.3...7.82
= 1.2.3...8.9 - 1.2.3...8.1 - 1.2.3...7.8.8
= 1.2.3...8.( 9 - 1 - 8 )
= 1.2.3...8.0
= 0
còn câu 2 và 3 thì sao
K ghi lại đề câu 2 nha :
\(=\frac{3^2.\left(2^2\right)^2.2^{32}}{11.2^{13}.\left(2^2\right)^{11}-\left(2^4\right)^9}\)
\(=\frac{3^2.2^4.2^{32}}{11.2^{13}.2^{22}-2^{36}}\)
\(=\frac{3^2.2^{36}}{11.2^{35}-2^{35}.2}\)
\(=\frac{3^2.2^{36}}{2^{35}\left(11-2\right)}\)
\(=\frac{3^2.2^{36}}{2^{35}.3^2}\)
\(=\frac{3^2}{3^2}.\frac{2^{36}}{2^{35}}\)
\(=1.2=2\)
Thuc hien cac phep tinh sau một cách hợp lí:
a) (10^2 + 11^2 + 12^2) : (13^2 + 14^2)
b) 1.2.3...9-1.2.3...8-1.2.3...7.8^2
c) (3.4.2^16)^2/11.2^13.4^11-16^9
d) 1152 - (374 + 1152) +(-65 + 374)
e) 13-12+11+10-9+8-7-6+5-4+3+2-1
Tính:
a)102+112+122/132+142
b)1.2.3...9-1.2.3...8-1.2.3...7.82
c)(3.4.216)2/11.213.411-169
d)1152-(374+1152)+(-65+374)
e)13-12+11+10-9+8-7-6+5-4+3+2-1
Giúp mình càng nhanh càng tốt nhé!!! Thank nhìu!
a)\(\left(10^2+11^2+12^2\right)\div\left(13^2+14^2\right)\)
\(=\left(100+121+144\right)\div\left(169+196\right)\)
\(=365\div365\)
\(=1\)
b) \(1.2.3...9-1.2.3...8-1.2.3...8^2\)
\(=1.2.3...8\left(9-1-8\right)\)
\(=1.2.3...8.0\)
\(=0\)
d) \(1152-\left(374+1152\right)+\left(-65+374\right)\)
\(=1152-374-1152-65+374\)
\(=\left(1152-1152\right)-65+\left(374-374\right)\)
\(=0-65+0\)
\(=-65\)
e) \(13-12+11+10-9+8-7-6+5-4+3+2-1\)
\(=13-\left(12-11\right)+\left(10-9\right)+\left(8-7\right)-\left(6-5\right)-\left(4-3\right)\)\(+\left(2-1\right)\)
\(=13-1+1+1-1-1+1\)
\(=13+0+0+0\)
\(=13\)
c)\(\frac{\left(3.4.2^{16}\right)^2}{11.2^{13}.4^{11}-16^9}\)
\(=\frac{3^2.\left(2^2\right)^2.\left(2^{16}\right)^2}{11.2^{13}.\left(2^2\right)^{11}-\left(2^4\right)^9}\)
\(=\frac{3^2.2^4.2^{32}}{11.2^{13}.2^{22}-2^{36}}\)
\(=\frac{3^2.2^{36}}{11.2^{35}-2^{36}}\)
\(=\frac{9.2^{36}}{2^{35}\left(11-2\right)}\)
\(=\frac{9.2^{36}}{2^{35}.9}\)
\(=3\)
a)(10^2+11^2+12^2):(13^2+14^2) b)1.2.3...9-1.2.3...8-1.2.3...7.8^2 c)(3.4.2)^16/11.2^13.4^11-16^9 d)1152-(374+1152)+(-56+374) e)13-12+11+10-9+8-7-6+5-4+3+2-1 |
thực hiện các phép tính sau một cách hợp lí:
a,\(\left(10^2+11^2+12^2\right):\left(13^2+14^2\right)\)
b,\(1.2.3...9-1.2.3...8-1.2.3...7.8^2\)
c,\(\frac{\left(3.4.2^{16}\right)^2}{11.2^{13}.4^{11}-16^9}\)
d,1152-(374+1152)+(-65+374)
e,13-12+11+10-9+8-7-6+5-4+3-2-1
a) =\(\left[\left(12+1\right)^2+\left(12+2\right)^2\right]:\left(13^2+14^2\right)\)
=1
b)=(1.2.3....8).(9-1-8)
=(1.2.3....8).0
=0
mik chỉ giải được zậy thôi.
t mik nha.
thực hiện các phép tính sau một cách hợp lí:
\(\left(10^2+11^2+12^2\right):\left(13^2+14^2\right)\)
1.2.3.....................9 - 1.2.3......8 - 1.2.3........7.\(^{8^2}\)
\(\frac{\left(3.4.2^{16}\right)^2}{11.2^{13}.4^{11}-16^9}\)
1152 - (374 + 1152 ) + (-65 + 374)
13 - 12 + 11 + 10 - 9 + 8 - 7 - 6 + 5 - 4 + 3 + 2 - 1
(10*2+11*2+12*2):(13*2+14*2)=100+121+144):(169+196)=1
Câu 1: Thực hiện phép tính
a) A= 1.2.3...9-1.2.3...8-1.2.3...8\(^2\)
Câu 2 : Tính nhanh
[(11,81+8,19).0,02] : [(-9):11.25]:\(\frac{23^{10}-23^{11}}{23^{11}+21.23^{10}}\)
Câu 1 :
A= 1.2.3...9-1.2.3...8-1.2.3...82
= 1.2.3...8. ( 9 - 1 - 8 )
= 1.2.3...8.0
= 0