Tinh:
1/50 - 1/50 x 49 - 1/49x48-............-1/3x2 - 1/2x1
(1\(^2\) -1000) x ( 2\(^2\)x1000)........... ( 101\(^2\)-1000)
Bài 3 : Tính nhanh :
a ) A = 2 + 4 + 6 + 8 + ....+ 1000
b ) 1/ 20 + 1/30 + 1/42 + 1/50 + 1/72 + 1/90 + 1/110 + 1/132
c ) 2 / 1x3 + 2 / 3x5 + 2/5 x 7 + .....+ 2 / 97 x 99 + 2/99 x 101
a) A = 2 + 4 + 6 + 8 + ... + 1000
Ta có : A = 2 + 4 + 6 + 8 + ... + 1000 ( có 500 số )
= (1000 + 2) . 500 : 2 = 250500
c) \(\frac{2}{1.3}+\frac{2}{3.5}+\frac{2}{5.7}+...+\frac{2}{97.99}+\frac{2}{99.101}\)
\(=1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{97}-\frac{1}{99}+\frac{1}{99}-\frac{1}{101}\)
\(=1-\frac{1}{101}=\frac{100}{101}\)
Tinh : (1000-1^3)*(1000-2^3)*(1000-3^3)....(1000-50^3)
Tinh:(1000-1^3).(1000-2^3).(1000-3^3).....(1000-50^3)
Ta có:
\(A=\left(1000-1^3\right).\left(1000-2^3\right).........\left(1000-50^3\right)\)
\(A=\left(1000-1^3\right).\left(1000-2^3\right).......\left(1000-10^3\right)........\left(1000-50^3\right)\)
\(A=0.\left(1000-1^3\right).\left(1000-2^3\right)....\left(1000-9^3\right).\left(1000-11^3\right).....\left(1000-50^3\right)\)
A = 0
tinh:(1000-1^3).(1000-2^3).(1000-3^3)...(1000-50^3)
Tính nhanh :
1 . ( 19 x 43 - 26928 : 33 ) x ( 16112 : 53 - 10,1 x 30 )
2. 1996 x 1995 - 996 + 1000 - 1996 x 1994
3. ( 1 + 2 + 4 + ... + 512 ) x ( 101 x 102 - 101 x 101 - 50 - 51 )
4. 10,09 x 100 + 2009 + 200,9 : 0,1 + 2,009 : 0,001
1=ĐS=1
2=ĐS=2000
3=ĐS=0
4=ĐS=7036
K MÌNH NHA
Tinh nhanh
a,A=2018^(1*9*4*6)*(9*4*7)***(1*9*9*9)
b,B=(1000—1^3)*(1000—2^3)*(1000—3^3)***(1000—50^3)
Bài 1: Tính nhanh
A, 13 x 126 + 37 x 126 - 49 x 126
B, ( 1 + 2 + 4 + 8+.....+ 512 ) x ( 101 x 102 - 101 x 101 - 50 - 51 )
Bài 1: Tính nhanh
A, 13 x 126 + 37 x 126 - 49 x 126
= 126 x ( 13 + 49 - 49 )
= 126 x 1
= 126
B, ( 1 + 2 + 4 + 8+.....+ 512 ) x ( 101 x 102 - 101 x 101 - 50 - 51 )
= ( 1 + 2 + 4 + 8+.....+ 512 ) x ( 101 x ( 102 - 101 - 1))
= ( 1 + 2 + 4 + 8+.....+ 512 ) x ( 101 x 0)
= ( 1 + 2 + 4 + 8+.....+ 512 ) x 0
= 0
Tính nhanh: (1000 - 13 ) x (1000 - 23 ) x ( 1000 - 33 ) x ...........x (1000 - 503 )
(1000 - 13) x (1000 - 23) x (1000 - 33) x ... x (1000 - 103) x ... x (1000 - 503)
= (1000 - 13) x (1000 - 23) x (1000 - 33) x ... x (1000 - 1000) x ... x (1000 - 503)
= (1000 - 13) x (1000 - 23) x (1000 - 33) x ... x 0 x ... x (1000 - 503)
= 0
Tinh (1000 - 13) (1000 - 23) (1000 - 33) (1000 - 43) ..... (1000 - 503)
(1000 - 13)(1000 - 23)(1000 - 33)........(1000 - 503)
= (1000 - 13)(1000 - 23)(1000 - 33)....(1000 - 103)....(1000 - 503)
= (1000 - 13)(1000 - 23)(1000 - 33).....(1000 - 1000)...(1000 - 503)
= (1000 - 13)(1000 - 23)(1000 - 33).....0...(1000 - 503)
= 0