giúp mk với:
\(\left(1-2x\right)^4\)\(=\)\(\frac{1}{128}\)
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LS
1
26 tháng 9 2016
\(2x-\frac{5}{4}=\left(3-\frac{1}{2}\right)\left(x-\frac{1}{3}\right)\)
\(\Leftrightarrow2x-\frac{5}{4}=\frac{5}{2}\left(x-\frac{1}{3}\right)\)
\(\Leftrightarrow2x-\frac{5}{4}=\frac{5x}{2}-\frac{5}{6}\)
\(\Leftrightarrow-\frac{x}{2}-\frac{5}{12}=0\)
\(\Leftrightarrow-\frac{x}{2}=\frac{5}{12}\Rightarrow-12x=10\)
\(\Rightarrow x=-\frac{5}{6}\)
H2
1
29 tháng 3 2020
\(\left|\left(x+\frac{1}{2}\right)\right|\left|2x-\frac{3}{4}\right|=2x-\frac{3}{4}\)
Do VT \(\ge\)0 => VP \(\ge\)0
=> \(2x-\frac{3}{4}\ge0\)
=> \(x\ge\frac{3}{8}\Rightarrow x+\frac{1}{2}\ge0\)
Vậy PT đã cho <=> \(\left(x+\frac{1}{2}\right)\left(2x-\frac{3}{4}\right)=2x-\frac{3}{4}\)
\(\Leftrightarrow\left(x+\frac{1}{2}\right)\left(2x-\frac{3}{4}\right)-\left(2x-\frac{3}{4}\right)=0\)
\(\Leftrightarrow\left(x+\frac{1}{2}-1\right)\left(2x-\frac{3}{4}\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x+\frac{1}{2}-1=0\\2x-\frac{3}{4}=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=\frac{1}{2}\\x=\frac{3}{8}\end{cases}}}\)
14 tháng 7 2016
a) (2+1)(2^2+1)(2^4+1)...(2^32+1)-2^64
=(2+1)(2-1)(2^2+1)(2^4+1)...(2^32+1)-2^64
=(2^2-1)(2^2+1)(2^4+1)...(2^32+1)-2^64
=(2^4-1)(2^4+1)....(2^32+1)-2^64
=......
=(2^32-1)(2^32+1)-2^64
=2^64-1-2^64=-1
b)Đặt A=(5+3)(5^2+3^2)(5^4+3^4)...(5^64+3^64)+(5^128-3^128)/2
đặt B=(5+3)(5^2+3^2)(5^4+3^4)...(5^64+3^64)
\(2B=\left(5-3\right)\left(5+3\right)\left(5^2+3^2\right)\left(5^4+3^4\right)...\left(5^{64}+3^{64}\right)\)
\(2B=\left(5^2-3^2\right)\left(5^2+3^2\right)\left(5^4+3^4\right)...\left(5^{64}+3^{64}\right)\)
\(2B=\left(5^4-3^4\right)\left(5^4+3^4\right)...\left(5^{64}+3^{64}\right)\)
\(2B=.......\)
2B=(5^64-3^64)(5^64+3^64)
2B=5^128-3^128
B=(5^128-3^128)/2 (thế vào đề bài)
=> A=B+(5^128-3^128)/2=(5^128-3^128)/2+(5^128-3^128)/2=\(\frac{2\left(5^{128}-3^{128}\right)}{2}=\left(5^{128}-3^{128}\right)\)
14 tháng 7 2016
a) A = ( 2-1)(2+1)(22+1)...(232+1)-264
=(22-1)(22+1)(24+1)... -264
=....
=264-1-264=1
câu b tương tự nhá
GIẢI CHI TIẾT RA GIÚP MK VS NHÉ!!!!MK RẤT CẢM ƠN
PA
17 tháng 7 2016
a.
\(\left(x+\frac{1}{2}\right)\times\left(x-\frac{3}{4}\right)=0\)
TH1:
\(x+\frac{1}{2}=0\)
\(x=-\frac{1}{2}\)
TH2:
\(x-\frac{3}{4}=0\)
\(x=\frac{3}{4}\)
Vậy \(x=-\frac{1}{2}\) hoặc \(x=\frac{3}{4}\)
b.
\(\left(\frac{1}{2}x-3\right)\times\left(\frac{2}{3}x+\frac{1}{2}\right)=0\)
TH1:
\(\frac{1}{2}x-3=0\)
\(\frac{1}{2}x=3\)
\(x=3\div\frac{1}{2}\)
\(x=3\times2\)
\(x=6\)
TH2:
\(\frac{2}{3}x+\frac{1}{2}=0\)
\(\frac{2}{3}x=-\frac{1}{2}\)
\(x=-\frac{1}{2}\div\frac{2}{3}\)
\(x=-\frac{1}{2}\times\frac{3}{2}\)
\(x=-\frac{3}{4}\)
Vậy \(x=6\) hoặc \(x=-\frac{3}{4}\)
c.
\(\frac{2}{3}-\frac{1}{3}\times\left(x-\frac{3}{2}\right)-\frac{1}{2}\times\left(2x+1\right)=5\)
\(\frac{2}{3}-\frac{1}{3}x+\frac{1}{2}-x-\frac{1}{2}=5\)
\(\left(\frac{1}{2}-\frac{1}{2}\right)-\left(\frac{1}{3}x+x\right)=5-\frac{2}{3}\)
\(-\frac{4}{3}x=\frac{13}{3}\)
\(x=\frac{13}{3}\div\left(-\frac{4}{3}\right)\)
\(x=\frac{13}{3}\times\left(-\frac{3}{4}\right)\)
\(x=-\frac{13}{4}\)
d.
\(4x-\left(x+\frac{1}{2}\right)=2x-\left(\frac{1}{2}-5\right)\)
\(4x-x-\frac{1}{2}=2x-\frac{1}{2}+5\)
\(4x-x-2x=\frac{1}{2}-\frac{1}{2}+5\)
\(x=5\)
\(\left(1-2x\right)^4=\frac{1}{128}\)
\(\Leftrightarrow1-2x=\frac{\sqrt[4]{2}}{4}\)
\(\Leftrightarrow2x=\frac{1-\sqrt[4]{2}}{4}\)
hay \(x=\frac{1-\sqrt[4]{2}}{8}\)
số 1/128 ko tach dc mũ 4