1\(\frac{8}{15}\)-\(\frac{2}{3}\)x=0.2
\(\frac{23}{15}\)- \(\frac{2}{3}\)x=\(\frac{2}{10}\)
\(\frac{2}{3}\)x=\(\frac{23}{15}-\frac{2}{10}\)
\(\frac{2}{3}\)x=\(\frac{4}{3}\)
x=\(\frac{4}{3}:\frac{2}{3}\)
x=2
Vậy x=2
Bài 1:Tìm x,biết
a) \(x-\frac{20}{11.13}-\frac{20}{13.15}-\frac{20}{15.17}-...-\frac{20}{53.55}=\frac{3}{11}\)
b)\(x+\frac{15}{90.94}+\frac{15}{94.98}+\frac{15}{98.102}+...+\frac{15}{146.150}=\frac{2}{3}\)
c)\(x-\frac{1}{2}-\frac{1}{6}-\frac{1}{12}-\frac{1}{20}-\frac{1}{30}-\frac{1}{42}-\frac{1}{56}=\frac{5}{24}\)
d)\(8-\frac{8-\frac{8}{5}+\frac{8}{25}-\frac{8}{125}}{9-\frac{9}{5}+\frac{9}{25}-\frac{9}{125}}:\frac{161616}{151515}=\frac{4+\frac{4}{73}-\frac{4}{115}}{5+\frac{5}{73}-\frac{1}{23}}\)
Bài 1 : Chứng tỏ rằng : \(\frac{14n+3}{21n+5}\) là phân số tối giản với mọi n ϵ Z
Bài 2 Tìm x , biết
30 : \(\left(\frac{1}{4}x+\frac{3}{4}x\right)^2=\frac{5}{6}\)
Bài 3 Tính tích : A= \(\frac{3}{4}.\frac{8}{9}.\frac{15}{16}...\frac{899}{900}\)
tìm x biết
a)
\(\frac{1}{2}\)+\(\frac{2}{3}\).x=\(\frac{4}{5}\)
b)
x+\(\frac{1}{4}\)=\(\frac{4}{3}\)|
c)
\(\frac{3}{5}x-\frac{1}{2}=-\frac{1}{7}\)
|d)
\(\left|x+5\right|-6=9\)
e)
\(\left|x-\frac{4}{5}\right|=\frac{3}{4}\)
f)
\(\frac{1}{2}-\left|x\right|=\frac{1}{3}\)
g)
\(^{x^2}\)=16
h)
\(\left(x-\frac{1}{2}\right)^3=\frac{1}{27}\)
i)
\(^{3^3}\).x=\(^{3^6}\)
j)
\(\frac{1,35}{0,2}=\frac{1,25}{x}\)
k)
\(1\frac{2}{3}:x=6:0,3\)
$\frac{-3}{8}$ . $\frac{2}{15}$ + $\frac{-3}{8}$ . $\frac{13}{15}$ + 1$\frac{3}{8}$
Thực hiện phép tính
\(a,(\frac{-5}{28}+1,75+\frac{8}{35}).(-3\frac{9}{20})\) \(b,(6-2\frac{4}{5}).3\frac{1}{8}-1\frac{3}{5}:\frac{1}{4}\)
\(c,(\frac{7-5}{24}+0,75+\frac{7}{12}):(-2\frac{1}{8})\) \(d,8\frac{2}{7}-(3\frac{4}{7}+4\frac{2}{7})\)
\(e,\left(-3,2\right).\frac{-15}{64}+(0,8-2\frac{4}{15}):3\frac{2}{3}\) \(f,1\frac{13}{15}.\left(0,5\right)^2.3+(\frac{8}{15}-1\frac{19}{60}):1\frac{23}{24}\)
\(g,1,4.\frac{15}{49}-(\frac{4}{5}+\frac{2}{3}):2\frac{1}{5}\)
a) \(1-\left(5\frac{3}{8}+x-7\frac{5}{24}\right):\left(-16\frac{2}{3}\right)=0\)
b) \(\left(\frac{x}{3}-5\frac{1}{4}\right)^2-\frac{-2}{5}=1\frac{1}{25}\)
c) \(\frac{17-x}{12}=\frac{3}{17-x}\)
d) \(1\frac{1}{3}-25\%\left(x-\frac{8}{3}\right)+2x=1,6:\frac{3}{5}\)
Bài 1:Chứng tỏ rằng
a)\(\frac{1}{1.2}+\frac{1}{2.3}+...+\frac{1}{2009.2010}< 1\)
b)\(\frac{1}{2^2}+\frac{1}{3^2}+\frac{1}{4^2}+...+\frac{1}{100^2}< 1\)
c)\(\frac{2}{5}< \frac{1}{2^2}+\frac{1}{3^2}+\frac{1}{4^2}+...+\frac{1}{9^2}< \frac{8}{9}\)
d)\(\frac{1}{3}-\frac{2}{3^2}+\frac{3}{3^3}-\frac{4}{3^4}+...+\frac{99}{3^{99}}-\frac{100}{3^{100}}< \frac{3}{16}\)
Bài 2:Cho M=\(\frac{1}{15}+\frac{1}{105}+\frac{1}{315}+..+\frac{1}{9177}\).So sánh với 12
Bài 3:Với giá trị nào của x \(\in\) Z các phân số sau có giá trị là 1 số nguyên
a)A=\(\frac{3}{x-1}\) b)B=\(\frac{x-2}{x+3}\) c)C=\(\frac{2x+1}{x-3}\) d)D=\(\frac{x^2-1}{x+1}\)
Bài 4:a) Chứng tỏ rằng các phân số sau tối giản với mọi số tự nhiên n
a)\(\frac{n+1}{2n+3}\) b)\(\frac{2n+3}{4n+8}\)
Mình đang cần gấp lắm ,làm ơn
a,\(\frac{-5}{6}\) - x = \(\frac{7}{12}\) + \(\frac{-1}{3}\)
b,\(\frac{x+3}{-15}\) = \(\frac{1}{3}\)
c, \(\frac{-15}{x-1}\)=\(\frac{-3}{5}\)
d,\(\frac{1}{2}\)x-\(\frac{2}{5}\)=\(\frac{1}{5}\)
e,-\(\frac{2}{3}\)x+\(\frac{1}{5}\)=\(\frac{1}{10}\)
f,\(\frac{4}{5}\)- \(\frac{1}{2}\)x = \(\frac{1}{10}\)
tìm x biết \(\frac{2}{3}x:\frac{1}{5}=1\frac{1}{5}:25\%\)
Tìm x\(\varepsilon\)biết \(\frac{4}{3}.\left(\frac{1}{6}-\frac{1}{2}\right)\)<x<\(\frac{2}{3}\).\(\left(\frac{-1}{6}+\frac{3}{4}\right)\)