Bai 1:a)Tim x biet\(\frac{1}{3}+\frac{1}{6}+\frac{1}{10}+...+\frac{2}{x\times\left(x+1\right)}=\frac{2009}{2011}\)
b)\(\left(x-1\right)\times f\left(x\right)=\left(x+4\right)\times f\left(x\right)\)voi moi x
Bai 2;Tim x;y;z biet a)\(\frac{y+z+1}{x}=\frac{x+z+2}{y}=\frac{x+y-3}{z}\) b)\(\frac{2x+1}{5}=\frac{3y-z}{7}=\frac{2x+3y-1}{6x}\)
Tìm x và y biết:
d)\(-1\frac{2}{3}-\left(\left|2x\right|+\frac{5}{6}\right)=\)\(-2\)e)\(\left(-\frac{1}{2}+\frac{1}{3}\right):\left|1-2x\right|-1\frac{1}{4}:\left(-\frac{5}{8}\right).\left(-\frac{1}{2}\right)^2=\frac{1}{3}\)
c)\(\left|2x-1\right|+\left|2y+1\right|+\left|2x-y\right|=0\)b)\(\left|2x-1\right|=2x-1\)
a)\(\left|x-3\right|=x+4\)
tim x :
\(a.\left|x+5\right|=\frac{1}{7}-\left|\frac{4}{3}-\frac{1}{6}\right|\)|
\(b.\left|x+\frac{2}{3}\right|=\frac{1}{2}-\left[\frac{1}{4}-\frac{2}{3}\right]\)đau [ ] là dấu ngoặc đơn nha!
\(c.\left|x-\frac{1}{5}\right|=\left|\frac{-5}{2}\right|-\left[\frac{1}{4}-\frac{2}{3}\right]\)đau [ ] là dấu ngoặc đơn nha!
\(d.\left|x-\frac{5}{2}\right|=\frac{4}{3}-\left[\frac{2}{3}-\frac{1}{6}\right]\)đau [ ] là dấu ngoặc đơn nha!
ai nhanh nhất mk tk !
Tim x, biet:
a/ \(3,8:\left(2.x\right)=\frac{1}{4}:2\frac{2}{3}\)
b/ \(\left(0,25.x\right):3=\frac{5}{6}:0,125\)
c/ \(0,01:2,5=\left(0,75.x\right):0,75\)
d/ \(1\frac{1}{3}:0,8=\frac{2}{3}:\left(0,1.x\right)\)
Tim so huu ti x
a)\(\frac{2}{3x}-\frac{3}{12}=\frac{4}{5}-\left(\frac{7}{x}-2\right)\))
b)\(\frac{1}{x-1}+\frac{-2}{3}\left(\frac{3}{4}-\frac{6}{5}\right)=\frac{5}{2-2x}\)
c)\(3-\frac{2}{2x-3}=\frac{2}{5}+\frac{2}{9-6x}-\frac{3}{2}\)
e)\(\frac{x}{2}-\frac{1}{x}=\frac{1}{12}\)
Bài 1 thực hiện phép tính
a)\(\frac{45}{19}-\left(\frac{1}{2}+\left(\frac{1}{3}+\left(\frac{1}{4}\right)^{-1}\right)^{-1}\right)^{-1}.\)
b) \(\frac{5.4^{15}.9^9-4.3^{20}.8^9}{5.2^{10}.6^{19}-7.2^{29}.27^6}.\)
Bài 2. tìm x, biết:
a) 2(x-1) - 3(2x+2) - 4(2x+3) =16
b) \(3\frac{1}{2}:\left|2x-1\right|=\frac{21}{22}\)
c) |x2+|x-1|| = x2+2
Bài 3. Chứng minh rằng số có dạng abcabc luôn chia hết cho 11
Bài 4.tính:
a) A = \(\left(\frac{0,4-\frac{2}{9}+\frac{2}{11}}{1,4-\frac{7}{9}+\frac{7}{11}}-\frac{\frac{1}{3}-0,25+\frac{1}{5}}{1\frac{1}{6}-0,875+0,7}\right):\frac{2012}{2013}\)
b) B =\(4.\left(-\frac{1}{2}\right)^2-2.\left(-\frac{1}{2}\right)^2+3.\left(-\frac{1}{2}\right)+1\)
c) C =\(\frac{1}{2}:\left(-1\frac{1}{2}\right):1\frac{1}{3}:\left(-1\frac{1}{4}\right):1\frac{1}{5}:\left(-1\frac{1}{6}\right):...:\left(-1\frac{1}{100}\right)\)
d) D =\(\frac{4^6.9^5+6^9.120}{-8^4.3^{12}+6^{11}}\)
tim x biet :
a )\(\frac{1}{5.8}+\frac{1}{8.11}+...+\frac{1}{x\left(x+3\right)}=\frac{101}{1540}\)
b) \(1+\frac{1}{3}+\frac{1}{6}+\frac{1}{10}+...+\frac{1}{x\left(x+1\right).2}=1\frac{1991}{1993}\)
tìm x biết
\(a,2\frac{1}{3}+\left(x-\frac{3}{2}\right)=\left(3-\frac{3}{2}\right).x\)
\(b,\frac{3}{2}:\left(x-1\frac{2}{3}\right)-5\frac{2}{3}=2\frac{5}{3}\)
\(c,\left(\frac{7}{2}-2x\right):3\frac{2}{5}+1\frac{4}{5}=7\frac{6}{5}\)
1. Chứng minh:
\(\frac{1}{2}+\frac{1}{3\sqrt{2}}+\frac{1}{4\sqrt{3}}+\frac{1}{5\sqrt{4}}+...+\frac{1}{2016\sqrt{2015}}<\frac{88}{45}\)
2. Rút gọn: A= \(\left(\frac{1+2x}{4+2x}-\frac{x}{3x-6}+\frac{2x^2}{13-3x^2}\right)\times\frac{24-12x}{6+13x}\)
3, Cho 2x;3y tỉ lệ nghịch với 3,4;x và z tỉ lệ thuận với 4,5; x-2y+3z=1. Tính x-y-z
4. Tìm x: \(\left(2x-3\right)^2-2\left(3x+1\right)^2=2x\left(x-2\right)+\left(x-1\right)\left(x+2\right)\)