Tính nhanh:
2/1.1*1.2 + 2/1.2*1.3 + 2/1.3*1.4 + 2/1.4*1.5 +...+2/2.5*2.6
Giúp mình nhanh nhanh nha!!!
THANH YOU VERY MUCH ^_^
tính nhanh:1.1+1.2.+1.3+1.4+1.5+,...,+1.17+1.18+1.19
tính nhanh :
(1.25-0.25*5)*(1.1*1.2*1.3*1.4*1.5)
( 1.1 x 1.2 x 1.3 x 1.4 x 1.5 x 1.6 ) x ( 1.25 - 0.25 x 5 ) giúp mk với
( 1.1 x 1.2 x 1.3 x 1.4 x 1.5 x 1.6 ) x ( 1.25 - 0.25 x 5 )
=( 1,1 x 1,2 x1,3 x1,4 x1,5 x1,6 ) x ( 1,25 - 1,25 )
=( 1.1x1,2 x1,3 x1,4 x1,5 x1,6 ) x 0
=0
#Toán lớp 5
1.1+1.2+1.3+1.4+1.5+....1.98+1.99+1.100
1.1. Ann……………..handball very well.
1.2. I never……………..coffee.
1.3. The swimming pool……………..at 7.00 in the morning.
1.4. It……………..at 9.00 in the evening.
1.5. Bad driving……………..many accidents
1.6. My parents……………..in a very small flat.
1.7. My students……………..a little English.
1.8. The Olympic Games……………..place every four years.
1.9. They are good students. They always……………..their homework.
1.10. I always……………..early in the morning.
1 plays
2 drink
3 opens
4 closes
5 causes
6 live
7 know
8 take
9 finish
10 get up
1. Ann…plays…………..handball very well.
2. I never…drink…………..coffee.
3. The swimming pool………opens……..at 7.00 in the morning.
4. It……closes………..at 9.00 in the evening.
5. Bad driving…causes…………..many accidents
6. My parents…live…………..in a very small flat.
7. My students……speak………..a little English.
8. The Olympic Games…take…………..place every four years.
9. They are good students. They always……do………..their homework.
10. I always……wake up………..early in the morning.
1. Ann…plays....handball very well.
2. I never…drink.......coffee.
3. The swimming pool…open…..at 7.00 in the morning.
4. It....closes…at 9.00 in the evening.
5. Bad driving…causes….many accidents
6. My parents…live….in a very small flat.
7. My students……speak…a little English.
8. The Olympic Games…take…...place every four year
9. They are good students. They always……do…their homework.
10. I always……wake up……early in the morning.
tính:
1.2+1.3+1.4+1.5=?
kết bạn tick luôn
mik đang rất buồn có ai trò chuyện ko
tính
1.2+1.3+1.4=?
a)1.2+1.3+1.4+1.5=2+3+4+5=14
b)1.2+1.3+1.4=2+3+4=9
tk nha+kb nx!
1 . 2 + 1 . 3 + 1 . 4 + 1 . 5
= 1 . ( 2 + 3 + 4 + 5 )
= 1 . 14
= 14
1 . 2 + 1 . 3 + 1 .4
= 1 . ( 2 + 3 + 4)
= 1 . 9
= 9
kb nha
1.2+1.3+1.4+1 5=?
Ae nhanh mk k
1.2+1.3+1.4+1 5=?
=2+3+4+5
=5+5+4
=10+4=14
1 . 2 + 1 . 3 + 1 .4 + 1 . 5
= 1 ( 2 + 3 + 4 + 5)
= 1 . 14
=14
1.2+1.4+.......+9.8
x*4+x*6+x*8+2016
1.1+1.3+1.5+...+9.9
Tính:
f) F=1.2+2.3+3.4+...+n(n+1)
g) G= 1.2.3+2.3.4+3.4.5+...+99.100.101
h) H= 1.2.3+2.3.4+3.4.5+...+n(n+1)(n+2)
i) I= 1.3+2.4+3.5+...+99.100
j) J= 1.4+2.5+3.6+...+99.102
Ai giải nhanh nhất chọn đầu tiên
3F= 1.2.(3-0)+ 2.3.(4-1)+...+ n.(n+1).[(n+2)-(n-1)]
=[1.2.3+ 2.3.4+...+ (n-1)n(n+1)+ n(n+1)(n+2)]- [0.1.2+ 1.2.3+...+(n-1)n(n+1)]
=n(n+1)(n+2)
=>F
H=1.2.3+2.3.4+3.4.5+...+n(n+1)(n+2)
=> 4H=1.2.3(4-0)+2.3.4(5-1)+...+n(n+1)(n+2)((n+3)-(n-1))
=1.2.3.4-0.1.2.3+2.3.4.5-1.2.3.4+...+n(n+1)(n+2)(n+3)-(n-1).n(n+1)(n+2)
=n(n+1)(n+2)(n+3)
Nhân biểu thức S với số 5, ta có:
5.S = 1.2.3.4.5 + 2.3.4.5.5 + 3.4.5.6.5 + ... + 97.98.99.100.5
Biểu diễn số 5 ở mỗi số hạng vế phải bằng phép trừ thích hợp: 5 = 5 - 0 = 6 - 1 = 7 - 2 = ... = 101 - 96, ta có
5.S = 1.2.3.4.(5 - 0) + 2.3.4.5.(6 - 1) + 3.4.5.6.(7 - 2) + ...+ 97.98.99.100.(101 - 96)
= (1.2.3.4.5 - 1.2.3.4.0) + (2.3.4.5.6 - 2.3.4.5.1) + (3.4.5.6.7 - 3.4.5.6.2) + ... + (97.98.99.100.101 - 97.98.99.100.96)
= 1.2.3.4.5 - 0.1.2.3.4 + 2.3.4.5.6 - 1.2.3.4.5 + 3.4.5.6.7 - 2.3.4.5.6 + ... + 97.98.99.100.101 - 96.97.98.99.100
= 97.98.99.100.101 - 0.1.2.3.4
= 97.98.99.100.101
Suy ra
S = 97.98.99.100.101/5 = 97.98.99.20.101. Đến đây thì bạn dùng máy tính bấm ra S=1901009880