giúp mk nhanh nha
72-16+8-32
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1/2 + 1/4 + 1/8 +1/16 + 1/32 + 1/64 + 1/128
= 2 . ( 1/2 + 1/4 + 1/8 + 1/16 + 1/32 + 1/64 + 1/128 )
= 1 + 1/2 + 1/4 + 1/8 + 1/16 + 1/32 + 1/64 - 1/128 + 1/2 + 1/4 + 1/8 + 1/16 + 1/32 + 1/64 + 1/128 ( Rồi giản ước )
= 1
#)Giải :
\(\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+\frac{1}{64}+\frac{1}{128}+\frac{1}{256}+\frac{1}{512}\)
\(=\frac{1}{2}-\frac{1}{4}+\frac{1}{4}-\frac{1}{8}+\frac{1}{8}-\frac{1}{16}+...+\frac{1}{256}-\frac{1}{512}\)
\(=\frac{1}{2}-\frac{1}{512}\)
\(=\frac{255}{512}\)
Lời giải
\(=\frac{1}{2}-\frac{1}{4}+\frac{1}{4}-\frac{1}{8}+\frac{1}{8}-\frac{1}{16}+...+\frac{1}{256}-\frac{1}{512}\)
\(=\frac{1}{2}-\frac{1}{512}\)
\(=\frac{255}{512}\)
\(\left(190-2.x\right):35+32=16\)
\(=>\left(190-2x\right):35=-16\)
\(=>190-2x=-560\)
\(=>2x=750\)
\(=>x=375\)
Ủng hộ nha các bạn
(190 - 2 x X) : 35 + 32 = 16
(190 - 2x) : 35 = 16 - 32
(190 - 2x) : 35 = -16
190 - 2x = -16 x 35
190 - 2x = -560
-2x = -560 - 190
-2x = -750
\(x=\frac{-750}{-2}=375\)
Đặt A = 1 + 2 + 4 + 8 + ..... + 1024
=> 2A = 2 + 4 + 8 + ..... + 2048
=> 2A - A = 2048 - 1
=> A = 2047
Đặt A = 1 + 2 + 4 + 8 + ... + 1024
=> 2A = 2 + 4 + 8 + ... + 2048
=> 2A - A = 2048 - 1
=> 2A = 2047
đặt \(A=\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+...+\frac{1}{256}\)
=> A=\(\frac{1}{2}+\frac{1}{2^2}+\frac{1}{2^3}+\frac{1}{2^4}+\frac{1}{2^5}+....+\frac{1}{2^8}\)
=> 2A=\(1+\frac{1}{2}+\frac{1}{2^2}+\frac{1}{2^3}+\frac{1}{2^4}+....+\frac{1}{2^7}\)
=> 2A-A=\(\left(1+\frac{1}{2}+\frac{1}{2^2}+\frac{1}{2^3}+....+\frac{1}{2^7}\right)-\left(\frac{1}{2}+\frac{1}{2^2}+\frac{1}{2^3}+....+\frac{1}{2^8}\right)\)
=> A=\(1-\frac{1}{2^8}\)
b: A=1/3+1/9+...+1/3^10
=>3A=1+1/3+...+1/3^9
=>A*2=1-1/3^10=(3^10-1)/3^10
=>A=(3^10-1)/(2*3^10)
c: C=3/2+3/8+3/32+3/128+3/512
=>4C=6+3/2+...+3/128
=>3C=6-3/512
=>C=1023/512
d: A=1/2+...+1/256
=>2A=1+1/2+...+1/128
=>A=1-1/256=255/256
a)524.[23+(-45)] + 524.(-45+123)
=524.(-22) + 524.78
=524.(-22+78)
=524.100
=52400
Có : ( 72 - 32 ) + 8 - 16
= 40 + 8 - 16
= 48 - 16
= 32
kết quả ra:32