Tính tổng 1 + 4 + 8 + 16 + 32 + 64 + 128.
Tính tổng: S= 1/2+1/4+ 1/8+ 1/16+1/32+1/64+1/128
Cộng thêm 1/2 vào biểu thức đã cho, có:
S + 1/2= 1/2+1/4+ 1/8+ 1/16+1/32+1/64+1/128
Nhận xét:
Tính tổng:
1/2+1/4+1/8+1/16+1/32+1/64+1/128
Đặt \(A=\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+\frac{1}{64}+\frac{1}{128}\)
\(\Rightarrow2A=1+\frac{1}{2}+\frac{1}{4}+\frac{1}{16}+\frac{1}{32}+\frac{1}{64}\)
\(\Rightarrow2A-A=1-\frac{1}{128}=\frac{127}{128}\)
Tính tổng S=1/2+3/4+7/8+15/16+31/32+63/64+127/128-6
Ta có :
\(S=\left(\frac{1}{2}+\frac{3}{4}+\frac{7}{8}+\frac{15}{16}+\frac{31}{32}+\frac{63}{64}+\frac{127}{128}\right)-6\)
\(S=\left(\frac{64}{128}+\frac{102}{128}+\frac{112}{128}+\frac{120}{128}+\frac{124}{128}+\frac{126}{128}+\frac{127}{128}\right)-6\)
\(S=\frac{64+102+112+120+124+126+127}{128}-6\)
\(S=\frac{775}{128}-6\)
\(S=\frac{775}{128}-\frac{768}{128}\)
\(S=\frac{7}{128}\)
S=1/2+3/4+7/8+15/16+31/32+63/64+127/128 -6
S= 1-1/2 + 1-1/4 + 1-1/8 + 1-1/16 + 1-1/32 + 1-1/64+ 1-1/128 - 6
S= (1+1+1+1+1+1+1-6)- (1/2+1/4+1/8+1/16 + 1/32+1/64+1/128)
S= 1- 111/128
S= 17/128
(Làm lụi nha bn)
S=1/128
-Học tốt-
#TLQA
Tính nhanh tổng sau:
1/2 + 1/4 + 1/8 + 1/16 + 1/32 + 1/64 + 1/128 + 1/256 + 1/512 + 1/1024
bằng 0,9990234375
tính nhanh 1+2+4+8+16+32+64+128
1+1
2+2
4+4
8+8
16+16
32+32
64+64
128+128
1+1=2
2+2=4
4+4=8
8+8=16
16+16=32
32+32=64
64+64=128
128+128=256
tk m nhé
tính tổng dưới đây bằng cách nhanh nhất:
1/2+1/4+1/8+1/16+1/32+1/64+1/128+1/256+1/512+1/1204
bằng 511/512
1. Tính nhanh tổng sau :
3/2 + 3/4 + 3/8 + 3/16 + 3/32 + 3/64 + 3/128 + 3/256 + 3/512 + 3/1024
\(\frac{3}{2}+\frac{3}{4}+\frac{3}{8}+\frac{3}{16}+\frac{3}{32}+\frac{3}{64}+\frac{3}{128}+\frac{3}{256}+\frac{3}{512}+\frac{3}{1024}\)
=\(3.\left(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+\frac{1}{64}+\frac{1}{128}+\frac{1}{256}+\frac{1}{512}+\frac{1}{1024}\right)\)
=\(3.\left(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{4}+\frac{1}{4}-\frac{1}{8}+\frac{1}{8}-\frac{1}{16}+\frac{1}{16}-\frac{1}{32}+\frac{1}{32}-\frac{1}{64}+\frac{1}{64}-\frac{1}{128}+\frac{1}{128}-\frac{1}{256}+\frac{1}{256}-\frac{1}{512}+\frac{1}{512}-\frac{1}{1024}\right)\)
=\(3.\left(1-\frac{1}{1024}\right)=3.\left(\frac{1024}{1024}-\frac{1}{1024}\right)=3.\frac{1023}{1024}=\frac{3069}{1024}\)
Chúc em học tốt
CON TRƯỚC SAI RUI MK NHẦM
1+1=?
2+2=?
4+4=?
8+8=?
16+16=?
32+32=?
64+64=?
128+128=?
1+1=2
2+2=4
4+4=8
8+8=16
16+16=32
32+32=64
64+64=128
128+128=256
1+1=2
2+2=44+4=8
8+8=16
16+16=32
32+32=64
64+64=128
128+128=256