rút gọn biểu thức sau A=(2+1)(2^2+1)...(2^64+1)+1
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NT
1
27 tháng 2 2015
A = (22 - 1) (22 +1)(24 +1)...(264 +1) + 1 = (24 - 1)(24 +1)...(264 +1) + 1 = (28 -1)...(264 +1) + 1 = 2128 -1 + 1 = 2128
LP
1
30 tháng 5 2016
B=3.(2^2+1)(2^4+1)...(2^64+1)
=(2^2-1)(2^2+1)(2^4+1)...(2^64+1)
=(2^4-1)(2^4+1)...(2^64+1)
=(2^8-1)...(2^64+1)
.......
=(2^64-1)(2^64+1)
=2^128-1
DN
1
T
7 tháng 10 2015
3(22+1)(24+1)(28+1)(216+1)(232+1)(264+1)
=(22-1)(22+1)(24+1)(28+1)(216+1)(232+1)(264+1)
=(24-1)(24+1)(28+1)(216+1)(232+1)(264+1)
=(28-1)(28+1)(216+1)(232+1)(264+1)
=(216-1)(216+1)(232+1)(264+1)
=(232-1)(232+1)(264+1)
=(264-1)(264+1)
=(2128-1)
Nếu thấy đúng thì thích cho mình nha
YS
2
29 tháng 6 2017
A = 3(2²+1)(2^4 + 1)....(2^64 + 1) + 1
= (2²-1)(2²+1)(2^4 + 1)....(2^64 + 1) + 1
= (2^4 - 1)(2^4 + 1)....(2^64 + 1) + 1
= (2^8 - 1).(2^8 + 1)(2^16 + 1)(2^32 + 1)(2^64 + 1) + 1
= (2^16 - 1)(2^16 + 1)(2^32 + 1)(2^64 + 1) + 1
= (2^32 - 1)(2^32 + 1)(2^64 + 1) + 1
= (2^64 - 1)(2^64 + 1) + 1 = 2^128 - 1 + 1 = 2^128.
29 tháng 6 2017
B = 3(2²+1)(2^4 + 1)....(2^64 + 1) + 1
= (2²-1)(2²+1)(2^4 + 1)....(2^64 + 1) + 1
= (2^4 - 1)(2^4 + 1)....(2^64 + 1) + 1
= (2^8 - 1).(2^8 + 1)(2^16 + 1)(2^32 + 1)(2^64 + 1) + 1
= (2^16 - 1)(2^16 + 1)(2^32 + 1)(2^64 + 1) + 1
= (2^32 - 1)(2^32 + 1)(2^64 + 1) + 1
= (2^64 - 1)(2^64 + 1) + 1 = 2^128 - 1 + 1 = 2^128.
BT
0
31 tháng 8 2023
1: Khi x=64 thì \(A=\dfrac{8+2}{8}=\dfrac{10}{8}=\dfrac{5}{4}\)
2: \(B=\dfrac{\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)+2\sqrt{x}+1}{\sqrt{x}\left(\sqrt{x}+1\right)}\)
\(=\dfrac{x-1+2\sqrt{x}+1}{\sqrt{x}\left(\sqrt{x}+1\right)}=\dfrac{\sqrt{x}\left(\sqrt{x}+2\right)}{\sqrt{x}\left(\sqrt{x}+1\right)}\)
\(=\dfrac{\sqrt{x}+2}{\sqrt{x}+1}\)
3: A/B>3/2
=>\(\dfrac{\sqrt{x}+2}{\sqrt{x}}:\dfrac{\sqrt{x}+2}{\sqrt{x}+1}-\dfrac{3}{2}>0\)
=>\(\dfrac{\sqrt{x}+1}{\sqrt{x}}-\dfrac{3}{2}>0\)
=>\(\dfrac{2\sqrt{x}+2-3\sqrt{x}}{\sqrt{x}\cdot2}>0\)
=>\(-\sqrt{x}+2>0\)
=>-căn x>-2
=>căn x<2
=>0<x<4
H9
HT.Phong (9A5)
CTVHS
31 tháng 8 2023
1) Thay x=64 vào A ta có:
\(A=\dfrac{2+\sqrt{64}}{\sqrt{64}}=\dfrac{2+8}{8}=\dfrac{5}{4}\)
2) \(B=\dfrac{\sqrt{x}-1}{\sqrt{x}}+\dfrac{2\sqrt{x}+1}{x+\sqrt{x}}\)
\(B=\dfrac{\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)}{\sqrt{x}\left(\sqrt{x}+1\right)}+\dfrac{2\sqrt{x}+1}{\sqrt{x}\left(\sqrt{x}+1\right)}\)
\(B=\dfrac{x-1}{\sqrt{x}\left(\sqrt{x}+1\right)}+\dfrac{2\sqrt{x}+1}{\sqrt{x}\left(\sqrt{x}+1\right)}\)
\(B=\dfrac{x-1+2\sqrt{x}+1}{\sqrt{x}\left(\sqrt{x}+1\right)}\)
\(B=\dfrac{x+2\sqrt{x}}{\sqrt{x}\left(\sqrt{x}+1\right)}\)
\(B=\dfrac{\sqrt{x}\left(\sqrt{x}+2\right)}{\sqrt{x}\left(\sqrt{x}+1\right)}\)
\(B=\dfrac{\sqrt{x}+2}{\sqrt{x}+1}\)
3) Ta có:
\(\dfrac{A}{B}>\dfrac{3}{2}\) khi
\(\dfrac{\sqrt{x}+2}{\sqrt{x}}:\dfrac{\sqrt{x}+2}{\sqrt{x}+1}>\dfrac{3}{2}\)
\(\Leftrightarrow\dfrac{\sqrt{x}+2}{\sqrt{x}}\cdot\dfrac{\sqrt{x}+1}{\sqrt{x}+2}>\dfrac{3}{2}\)
\(\Leftrightarrow\dfrac{\sqrt{x}+1}{\sqrt{x}}>\dfrac{3}{2}\)
\(\Leftrightarrow\dfrac{\sqrt{x}+1}{\sqrt{x}}-\dfrac{3}{2}>0\)
\(\Leftrightarrow\dfrac{2\sqrt{x}+2-3\sqrt{x}}{2\sqrt{x}}>0\)
\(\Leftrightarrow\dfrac{2-\sqrt{x}}{2\sqrt{x}}>0\)
Mà: \(2\sqrt{x}\ge0\forall x\)
\(\Leftrightarrow2-\sqrt{x}>0\)
\(\Leftrightarrow\sqrt{x}< 2\)
\(\Leftrightarrow x< 4\)
Kết hợp với đk:
\(0< x< 4\)
Q
6
8 tháng 8 2020
Bài làm:
Ta có: \(A=64-\left(x-4\right)\left(x^2+4x+16\right)\)
\(A=64-x^3+64\)
\(A=128-x^3\)
Tại \(x=-\frac{1}{2}\) ta được:
\(A=128-\left(-\frac{1}{2}\right)^3=\frac{1025}{8}\)
8 tháng 8 2020
A = 64 - ( x - 4 )( x2 + 4x + 16 )
A = 64 - ( x3 + 4x2 + 16x - 4x2 - 16x - 64 )
A = 64 - ( x3 - 64 )
A = 64 - x3 + 64
A = -x3 + 128
Thế x = -1/2 vào A ta được :
A = -(-1/2)3 + 128 = 1/8 + 128 = 1025/8
help mình nha
\(A=\left(2+1\right)\left(2^2+1\right)...\left(2^{64}+1\right)+1\)
\(A=\left(2-1\right)\left(2+1\right)\left(2^2+1\right)...\left(2^{64}+1\right)+1\)
\(A=\left(2^2-1\right)\left(2^2+1\right)\left(2^4+1\right)...\left(2^{64}+1\right)+1\)
\(A=2^{128}-1+1=2^{128}\)