\(\frac{x+1}{60}=\frac{\left(-15\right)}{x+1}\)
-4x(x-5)-2x(8-2x)=-3
\(\frac{x-1}{-15}=\frac{-60}{x-1}\)
\(\left(\frac{1}{4}x-1\right)+\left(\frac{5}{6}x-2\right)-\left(\frac{3}{8}x+1\right)=4,5\)
a/ -4x(x - 5) - 2x(8 - 2x) = -3
=> -4x2 + 20x - 16x + 4x2 = -3
=> 4x = -3
=> x = -3/4
b/ \(\frac{x-1}{-15}=-\frac{60}{x-1}\Rightarrow\left(x-1\right)^2=\left(-60\right)\left(-15\right)\)
\(\Rightarrow\left(x-1\right)^2=900\Rightarrow\orbr{\begin{cases}x-1=30\\x-1=-30\end{cases}\Rightarrow\orbr{\begin{cases}x=31\\x=-29\end{cases}}}\)
Vậy x = -29 , x = 31
\(x-15\%x=\left(\frac{8}{15}-1\frac{19}{60}\right):1\frac{23}{24}\)
Tìm x, biết
A.\(\left(-1\frac{1}{5}+x\right):\left(-3\frac{3}{5}\right)=-\frac{7}{4}+\frac{1}{4}:\frac{11}{8}\)
B.\(7,5x:\left(5\frac{195}{315}-8\right)=2\frac{13}{15}\)
C.\(60\%x+\frac{2}{3}x+x=688\)
D.\(1-\left(5\frac{3}{8}-x-7\frac{5}{24}\right):16\frac{2}{3}=0\)
M=\(\left(1-\frac{1}{3}\right)x\left(1-\frac{1}{6}\right)x\left(1-\frac{1}{10}\right)x\left(1-\frac{1}{15}\right)x\left(1-\frac{1}{21}\right)x\left(1-\frac{1}{28}\right)\)
\(\left(1-\frac{1}{3}\right)\)\(x\left(1-\frac{1}{6}\right)\)\(x\)\(\left(1-\frac{1}{10}\right)\)\(x\)\(\left(1-\frac{1}{15}\right)\)\(x\)\(\left(1-\frac{1}{21}\right)\)\(x\)\(\left(1-\frac{1}{28}\right)\)\(=\)\(\left(\frac{3}{3}-\frac{1}{3}\right)\)\(x\)\(\left(\frac{6}{6}-\frac{1}{6}\right)\)\(x\)\(\left(\frac{10}{10}-\frac{1}{10}\right)\)\(x\)\(\left(\frac{15}{15}-\frac{1}{15}\right)\)\(x\)\(\left(\frac{21}{21}-\frac{1}{21}\right)\)\(x\)\(\left(\frac{28}{28}-\frac{1}{28}\right)\)\(=\)\(\frac{2}{3}x\frac{5}{6}x\frac{9}{10}x\frac{14}{15}x\frac{20}{21}x\frac{27}{28}\)\(=\)\(\frac{2x5x9x14x20x27}{3x6x10x15x21x28}\)\(=\)\(\frac{2x5\left(3x3\right)x\left(2x7\right)x\left(5x4\right)x\left(3x3x3\right)}{3x\left(3x2\right)x\left(5x2\right)x\left(5x3\right)x\left(7x3\right)x\left(4x7\right)}\)\(=\)\(\frac{3}{7}\)
tìm x,biết:
a)\(\frac{2}{\left(x+2\right)\left(x+4\right)}+\frac{4}{\left(x+4\right)\left(x+8\right)}+\frac{6}{\left(x+8\right)\left(x+14\right)}=\frac{x}{\left(x+2\right)\left(x+14\right)}\)
b)\(\frac{x+1}{10}+\frac{x+1}{11}+\frac{x+1}{12}=\frac{x+1}{13}+\frac{x+1}{14}\)
c)\(\left(x+2\right)^2=\frac{38}{25}+\frac{9}{10}-\frac{11}{15}+\frac{13}{21}-\frac{15}{28}+\frac{17}{36}-...+\frac{197}{4851}-\frac{199}{4950}\)
giúp tớ với,huhu
Tìm x biết :\(\frac{1}{\left(x+2000\right)\left(x+2001\right)}+\frac{1}{\left(x+2001\right)\left(x+2002\right)}+...+\frac{1}{\left(x+2003\right)\left(x+2014\right)}=\frac{14}{15}\)
Áp dụng \(\frac{1}{n\left(n+1\right)}=\frac{1}{n}-\frac{1}{n+1}\) rút gọn rồi quy đồng làm nốt
Tính nhanh:
\(1\frac{13}{15}.\left(0,5\right)^2.3-\left(\frac{8}{15}+1\frac{19}{60}\right):1\frac{19}{60}\)
\(1\frac{13}{15}\cdot\left(0,5\right)^2\cdot3-\left(\frac{8}{15}+1\frac{19}{60}\right):1\frac{19}{60}\)
\(=\frac{28}{15}\cdot\frac{1}{4}\cdot\frac{3}{1}-\frac{37}{20}\cdot\frac{60}{79}\)
\(=\frac{7}{5}-\frac{111}{79}\)
\(=\frac{-2}{395}\)
=28/15.1/4.3-8/15-79/60.60/79
=7.4/15.1/4.3-8/15-1
=7/15.3-8/15-1
=21/15-8/15-1
=13/15-1
=-2/15
ko hc mà đòi có thi thì đúp
\(\left[x+\frac{1}{3}\right]+\left[x+\frac{1}{15}\right]+\left[x+\frac{1}{35}\right]+...+\left[x+\frac{1}{575}\right]\)
\(=11xx+\left[\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+\frac{1}{81}+\frac{1}{243}\right]\)
\(\left(x+\frac{1}{3}\right)+\left(x+\frac{1}{15}\right)+....+\left(x+\frac{1}{575}\right)=11x+\left(\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+\frac{1}{81}+\frac{1}{243}\right)\)
\(13x+\left(\frac{1}{1.3}+\frac{1}{3.5}+.....+\frac{1}{23.25}\right)=11x+\left(\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+\frac{1}{81}+\frac{1}{243}\right)\)
\(13x+\frac{1}{2}.\left(\frac{1}{1}-\frac{1}{25}\right)=11x+\left(\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+\frac{1}{81}+\frac{1}{243}\right)\)
\(2x+\frac{12}{25}=\frac{1}{3^1}+\frac{1}{3^2}+\frac{1}{3^3}+\frac{1}{3^4}+\frac{1}{3^5}\)
Đặt \(A=\frac{1}{3^1}+\frac{1}{3^2}+\frac{1}{3^3}+\frac{1}{3^4}+\frac{1}{3^5}\)
\(3A=1+\frac{1}{3^1}+\frac{1}{3^2}+\frac{1}{3^3}+\frac{1}{3^4}\)
\(3A-A=1-\frac{1}{3^5}=\frac{242}{243}=2A\)
=> \(A=\frac{121}{243}\)
=> \(2x+\frac{12}{25}=\frac{121}{243}\)
=> \(2x=\frac{121}{243}-\frac{12}{25}=\frac{109}{6075}\)
=> x = ......
\(\frac{3}{\left(x-4\right)\left(x-7\right)}+\frac{6}{\left(2-7\right)\left(x-13\right)}+\frac{15}{\left(x-13\right)\left(x-28\right)}-\frac{1}{x-28}=-\frac{1}{20}\)