1,Tính nhanh
a,3x\(\left(\frac{1}{7}+\frac{1}{3}-\frac{3}{14}\right):\frac{11}{14}\)
b,\(\left(\frac{21}{8}+\frac{1}{2}\right):\frac{5}{6}\)
3,Tìm x,biết
a,\(\frac{1}{3}+\frac{1}{6}+\frac{1}{10}+......+\frac{2}{x\cdot\left(x+1\right)}=\frac{2016}{2018}\)
b,720:\(720:[41-\left(2\cdot x-5\right)]=120\)
tìm x , biết :
a) 15 + 3 ( x - 1 ) = 36
b) \(\frac{2}{3}x+\left(1\frac{1}{9}\right)=\frac{23}{15}x\frac{5}{6}\)
tìm x,y :
\(\frac{1}{2}-\left(6\frac{5}{9}+x-\frac{117}{8}\right):\left(12\frac{1}{9}\right)=0\)
\(\left(y+\frac{1}{3}\right)+\left(y+\frac{2}{9}\right)+\left(y+\frac{1}{27}\right)+\left(y+\frac{1}{81}\right)=\frac{56}{81}\)
3. Tìm x, y để
a) \(D=-\left(3x+\frac{1}{5}\right)^4+\left(-\left(\frac{1}{2}y+3\right)^2\right)^3+1963\)đạt giá trị lớn nhất
b) \(E=\left(x-2\right)^2+\left(y+8\right)^2-2015\)đạt giá trị nhỏ nhất
\(A=\left(6:\frac{3}{5}-1\frac{1}{6}x\frac{6}{7}\right):\left(4\frac{1}{5}x\frac{10}{11}+5\frac{2}{11}\right)\)\(B=\left(1-\frac{1}{2}\right)x\left(1-\frac{1}{4}\right)x.......x\left(1-\frac{1}{2015}\right)x\left(1-\frac{1}{2016}\right)\)
\(C=5\frac{9}{10}:\frac{3}{2}-\left(2\frac{1}{3}x4\frac{1}{2}-2x2\frac{1}{3}\right):\frac{7}{4}\)
Tìm x biết
a) \(\frac{1,11+0,19-12.2}{0,296+0,094}-x=\left(\frac{1}{2}+\frac{1}{3}\right):2\)\(2\)
b) \(x:\left(3\frac{1}{2}-5\frac{1}{6}\right)=4\frac{1}{5}-6\frac{2}{3}\)
a)\(\left(1-\frac{1}{2}\right)x\left(1-\frac{1}{3}\right)x\left(1-\frac{1}{4}\right)x\left(1-\frac{1}{5}\right)x......x\left(1-\frac{1}{18}\right)x\left(1-\frac{1}{19}\right)x\left(1-\frac{1}{20}\right)\)
b)\(1\frac{1}{2}x1\frac{1}{3}x1\frac{1}{4}x1\frac{1}{5}x......x1\frac{1}{2005}x1\frac{1}{2006}x1\frac{1}{2007}\)
\(a,\frac{18}{17}-\left(\frac{7}{4}-\frac{1}{5}\right):\frac{1}{2}\)
\(b,\frac{8}{5}-\frac{1}{2}:\frac{1}{4}x\left(\frac{3}{7}+\frac{1}{4}\right)\)
Tìm x biết: \(\left(x+\frac{1}{2}\right)+\left(x+\frac{1}{4}\right)+\left(x+\frac{1}{8}\right)+\left(x+\frac{1}{16}\right)=1\)