P=1+1/2(1+2)+1/3(1+2+3)+...+1/16(1+2+3+...+16)
GIUP MINH NHANH NHA !!! MINH DANG CAN
cac ban giai giup minh bai nay voi , nhanh nha minh dang can gap
1/2+ 1/4 +1/8 + 1/16 + 1/32 + 1/64
tinh bang cach thuan tien nhat mha
\(=\frac{32+16+8+4+2+1}{64}=\frac{63}{64}\)
Tinh P giup minh voi : P = 1+1/2(1+2)+1/3(1+2+3)+1/4(1+2+3+4)+...+1/16(1+2+3+...+16) . Ban nao lam duoc thi giup minh nha . Minh se tick ung ho .
mong moi nguoi giup do minh dang can gap
a , 1/2+1/4+1/8+1/16+1/32
b , 2/1*2+2/2*3+2/3*4+...+2/18*19+2/19*20
a) Đặt \(A=\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}\)
\(2A=\left(\frac{1}{2}\times2\right)+\left(\frac{1}{4}\times2\right)+\left(\frac{1}{8}\times2\right)+\left(\frac{1}{16}\times2\right)+\left(\frac{1}{32}\times2\right)\)
\(2A=1+\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}\)
Ta lấy : \(2A-1A=1A\)
\(A=\left(1+\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}\right)-\left(\frac{1}{2}+\frac{1}{4}+\frac{1}{6}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}\right)\)
\(A=1-\frac{1}{32}\)
\(A=\frac{31}{32}\)
Vậy \(A=\frac{31}{32}\)
b) Đặt \(B=\frac{2}{1\times2}+\frac{2}{2\times3}+\frac{2}{3\times4}+...+\frac{2}{18\times19}+\frac{2}{19\times20}\)
\(B=2\times(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{18}-\frac{1}{19}+\frac{1}{19}-\frac{1}{20})\)
\(B=2\times\left(1-\frac{1}{20}\right)\)
\(B=2\times\frac{19}{20}\)
\(B=\frac{19}{10}\)
Vậy \(B=\frac{19}{10}\)
Học tốt # ^-<
Tính :
S1= 1-2+3-4+....................+2017-2018
S2= 1-4+7-10+..............+2015-2018
S3= 1+2-3-4+.....................+2015+2016-2017-2018
Giup minh voi minh dang can gap nha
ai nhanh ma dungthi minh tich cho nha
S1 = 1-2+3-4+....+2017-2018
= (-1)+(-1)+....+(-1)
= (-1) x 1009
= -1009
S3=2019 nha, mình ko kip viết cách giai
S1= (1-2)+(3-4)+............+(2017-2018)
=(-1).(-1).......(-1)
=(-1).1009
(-1009)
Mot doi xe phai cho mot khoi luong hang theo ke hoach . D ot 1 cho duoc 1/2 so hang , dot hai cho duoc 1/3 so hang , dot 3 cho not 16 tan hang thi hoan thanh.Hoi doi xe cho duoc nhieu tan hang theo ke hoach ?
ai nhanh giup minh voi minh dang can gap !!!!!
nhanh duoc 2 tick
16 tấn hàng ứng vs phân số :
1 - 1/2 - 1/3 = 1/6 ( vậy 16 tấn hàng ứng vs 1/6 )
Đội xe phải chở số tấn hàng là :
16 : 1/6 = 96 ( tấn hàng )
Đ/S : 96 tấn hàng
tui nha
giup minh voi
A=5+|1/3-x|
ai nhanh minh cho 2 tich nha
minh dang can gap
tim gia tri bieu thuc sao cho la so nho nhat
Với x < 1/3 thì :A= 5+1/3 - x = 16/3 - x
với x\(\ge\)1/3 thì A= 5 + x -1/3 = x+ 14 /3
C=3+(3/1+2)+(3/1+2+3)+(3/1+2+3+4)+...+(3/1+2+3+...+100)
minh dang can gap mong cac ban giup minh T_T
tinh nhanh
A=1*1+2*2+3*3+...+99*99+100*100
giup minh nhanh nha
minh dang can gap
ai giai nhanh nhat minh tik cho
A=1.1+2.2+3.3+...+99.99+100.100
3A=1.2.3+2.3.(4-1)+...99.100.(101-98)
3A=1.2.3+2.3.4-1.2.3+...+99.100.101-98.99.100
3A=99.100.101=999900
A= 999900:3=333300
\(A=1^2+2^2+3^2+...+100^2\)
\(\Rightarrow A=1\left(2-1\right)+2\left(3-1\right)+3\left(4-1\right)+...+100\left(101-1\right)\)
\(\Rightarrow A=1.2-1+2.3-2+3.4-3+...+100.101-100\)
\(\Rightarrow A=1.2+2.3+...+100.101-\left(1+2+3+...+100\right)\)
\(\Rightarrow A=\frac{100.101.102}{3}-\frac{\left(100+1\right)\left[\left(100-1\right):1+1\right]}{2}=\frac{100.101.102.2}{6}-\frac{101.100.3}{6}\)
\(\Rightarrow A=\frac{100.101\left(102.2-3\right)}{6}\)
Chung minh dang thuc
x^31+x^30+.....+x+1=(1+x)(1+x^2)(1+x^4)...(1+x^16)
Giup minh nha
\(\left(1-x\right)\left(x^{31}+x^{30}+...+x+1\right)=\left(1-x\right)\left(1+x\right)\left(1+x^2\right).....\left(1+x^{16}\right)\)
VP = 1 - x32
Đặt \(A=x^{31}+x^{30}+..+x+1\Leftrightarrow xA=x^{32}+x^{31}+.......+x^2+x\)
VT = \(A-xA=\left(1-x\right)A=1-x^{32}\)= VP (dpcm)