Tìm dấu thích hợp ( > , < ) thay cho dấu " ? ".
a) \(\dfrac{-2}{9}?\dfrac{-7}{9}\)
b) \(\dfrac{5}{7}?\dfrac{-10}{7}\)
Làm giúp mik nha ! Thanks. Hi hi ^_^
Điền dấu thích hợp (>,<,=) vào chỗ trống.
a,\(\dfrac{-3}{5}+\dfrac{-11}{5}...\dfrac{-7}{3}+\dfrac{4}{7}\)
b,\(\dfrac{-7}{11}+\dfrac{-15}{11}...\dfrac{-4}{3}+\dfrac{-7}{5}\)
Giúp mk nha :>>. Mk cảm ơn.
(Bạn nào biết thì giải giúp mình nhé, lưu ý dấu "." là dấu nhân)
Tìm x, biết:
a) -\(\dfrac{5}{6}\) - x = \(\dfrac{2}{3}\)
b) \(\dfrac{2}{3}\)x + \(\dfrac{1}{2}\) = \(\dfrac{1}{10}\)
c) \(\dfrac{2}{9}\) - \(\dfrac{7}{8}\) . x = \(\dfrac{1}{3}\)
d) \(\dfrac{4}{5}\) + \(\dfrac{5}{7}\) : x = \(\dfrac{1}{6}\)
e) (\(\dfrac{2}{5}\) - \(1\dfrac{2}{3}\)) : x - \(\dfrac{3}{5}\) = \(\dfrac{2}{5}\)
f) 1 - (-\(\dfrac{3}{4}\) + x) . \(2\dfrac{2}{3}\) = 0
Lời giải:
a.
$x=\frac{-5}{6}-\frac{2}{3}=\frac{-3}{2}$
b.
$\frac{2}{3}x=\frac{1}{10}-\frac{1}{2}=\frac{-2}{5}$
$x=\frac{-2}{5}: \frac{2}{3}=\frac{-3}{5}$
c.
$\frac{7}{8}x=\frac{2}{9}-\frac{1}{3}=\frac{-1}{9}$
$x=\frac{-1}{9}: \frac{7}{8}=\frac{-8}{63}$
d.
$\frac{5}{7}: x=\frac{1}{6}-\frac{4}{5}=\frac{-19}{30}$
$x=\frac{5}{7}: \frac{-19}{30}=\frac{-150}{133}$
e.
$(\frac{2}{5}-1\frac{2}{3}):x=\frac{2}{5}+\frac{3}{5}=1$
$\frac{-19}{15}: x=1$
$x=\frac{-19}{15}:1 =\frac{-19}{15}$
f.
$(-\frac{3}{4}+x).2\frac{2}{3}=1$
$\frac{-3}{4}+x=1: 2\frac{2}{3}=\frac{3}{8}$
$x=\frac{3}{8}+\frac{3}{4}=\frac{9}{8}$
Điền dấu > ; < hoặc = vào chỗ chấm cho thích hợp:
a) \(\dfrac{3}{4}.....\dfrac{4}{5}\) b) \(\dfrac{11}{12}.....\dfrac{7}{8}\) c) \(\dfrac{5}{7}+\dfrac{3}{5}.....\dfrac{6}{7}:\dfrac{5}{8}\) d) \(\dfrac{9}{16}-\dfrac{5}{9}.....\dfrac{1}{16}x\dfrac{1}{9}\)
Thay dấu "?" bằng số thích hợp
a) \(\dfrac{1}{2}=\dfrac{?}{8}\)
b) \(\dfrac{{ - 6}}{9} = \dfrac{{18}}{?}\)
a)
\(\dfrac{1}{2}=\dfrac{?}{8}\Rightarrow 1.8=2.?\Rightarrow ?=4 \)
b)
\(\dfrac{{ - 6}}{9} = \dfrac{{18}}{?}\Rightarrow(-6).?=9.18 \Rightarrow ?=-27\)
Tìm x:
a) \(\dfrac{x-3}{x+5}=\dfrac{5}{7}\) b) \(\dfrac{7}{x-1}=\dfrac{x+1}{9}\)
mọi người ơi giúp mik với ai làm đc mik tick cho
a) \(\dfrac{x-3}{x+5}=\dfrac{5}{7}\)
⇔\(7\left(x-3\right)=5\left(x+5\right)\)
⇔\(7x-21=5x+25\)
⇔\(7x-21-5x-25=0\)
⇔\(2x-46=0\)
⇔\(2x=46\)
⇔\(x=23\)
b) \(\dfrac{7}{x-1}=\dfrac{x+1}{9}\)
⇔\(\left(x+1\right)\left(x-1\right)=7.9\)
⇔\(x^2-1=63\)
⇔\(x^2=64=8^2\)
⇔\(\left[{}\begin{matrix}x=8\\x=-8\end{matrix}\right.\)
\(a.\dfrac{x-3}{x+5}=\dfrac{5}{7}\)
\(\left(x-3\right).7=\left(x+5\right).5\)
\(\left(x.7\right)+\left[\left(-3\right).7\right]=\left(x.5\right)+\left(5.5\right)\)
\(7x-21=5x+25\)
\(7x-5x=25+21\)
\(2x=46\)
\(x=46:2\)
\(x=23\)
Câu b/ cứ làm theo câu a/ là được
AcCl3 và NiCl2
a, x =\(\dfrac{-2}{7}\) +\(\dfrac{9}{7}\)
b,\(\dfrac{x}{3}\) =\(\dfrac{2}{5}\) +\(\dfrac{-4}{3}\)
Làm giúp mik vs mình đang cần gấp!
a) \(x=\dfrac{-2}{7}+\dfrac{9}{7}=1\)
b) \(\dfrac{x}{3}=\dfrac{2}{5}+\dfrac{-4}{3}\)
\(\dfrac{x}{3}=\dfrac{-14}{15}\)
\(\Rightarrow x=\dfrac{3.-14}{15}=\dfrac{-14}{5}\)
\(x=\dfrac{-2}{7}+\dfrac{9}{7}\)
\(x=1\)
Tìm phân số \(\dfrac{a}{b}\):
\(\dfrac{2}{7}\) x \(\dfrac{a}{b}\) + \(\dfrac{a}{b}\) x \(\dfrac{5}{7}\) = \(\dfrac{5}{7}\)
các bạn làm nhanh giúp mik nhé! mik cảm ơn
\(\Rightarrow\dfrac{a}{b}\times\left(-\dfrac{2}{7}+\dfrac{5}{7}\right)=\dfrac{5}{7}\\ \Rightarrow\dfrac{a}{b}\times\dfrac{3}{7}=\dfrac{5}{7}\\ \Rightarrow\dfrac{a}{b}=\dfrac{5}{7}:\dfrac{3}{7}\\ \Rightarrow\dfrac{a}{b}=\dfrac{5}{3}\\ \Rightarrow a=5;b=3\)
\(=>\dfrac{a}{b}\times\left(-\dfrac{2}{7}+\dfrac{5}{7}\right)=\dfrac{5}{7}\)
\(=>\dfrac{a}{b}\times\dfrac{3}{7}=\dfrac{5}{7}=>\dfrac{a}{b}=\dfrac{5}{7}:\dfrac{3}{7}=\dfrac{5}{3}\)
vậy \(\dfrac{a}{b}=\dfrac{5}{3}\)
Tìm 1 phân số \(\dfrac{x}{y}\) sao cho: \(\dfrac{7}{9}\)<\(\dfrac{x}{y}\)<\(\dfrac{7}{8}\) giải thích hộ mik luôn nha!
ét o ét
\(\dfrac{7}{9}< \dfrac{x}{y}< \dfrac{7}{8}\)
\(\dfrac{56}{72}< \dfrac{x}{y}< \dfrac{63}{72}\)
\(\dfrac{x}{y}=\left\{\dfrac{57}{72};\dfrac{58}{72};\dfrac{59}{72};\dfrac{60}{72};\dfrac{61}{72};\dfrac{62}{72}\right\}\)
Bài 1:
a)\(\dfrac{5}{7}\)+(\(\dfrac{3}{5}\)+\(\dfrac{-5}{7}\)) b)\(\dfrac{-3}{4}\)-\(\dfrac{15}{14}\):\(\dfrac{-5}{7}\)+\(^{\left(-1\right)^2}\) c)/\(\dfrac{-5}{9}\)/+\(^{\left(\dfrac{-2}{3}\right)^2}\).(20%-1,2)
Giups mik làm 3 câu này ạ.
a, \(\dfrac{5}{7}+\left(\dfrac{3}{5}+\dfrac{-5}{7}\right)\)
\(=\dfrac{5}{7}+\dfrac{-5}{7}+\dfrac{3}{5}
=0+\dfrac{3}{5}=\dfrac{3}{5}\)
b, \(=\dfrac{-3}{4}-\dfrac{15}{14}:\dfrac{-5}{7}+\left(-1\right)^2=\dfrac{-3}{4}-\dfrac{-3}{2}+1=\dfrac{-3}{4}-\dfrac{-6}{4}+1=\dfrac{3}{4}+1=\dfrac{7}{4}\)
c, \(\dfrac{-5}{9}+\left(\dfrac{-2}{3}\right)^2.\left(20\%-1.2\right)=\dfrac{-5}{9}+\dfrac{4}{9}x\left(\dfrac{1}{5}-\dfrac{6}{5}\right)=\dfrac{-5}{9}+\dfrac{4}{9}x\left(-1\right)=\dfrac{-5}{9}+\dfrac{-4}{9}=-1\)
Bài 1:
a) \(\dfrac{5}{7}+\left(\dfrac{3}{5}+\dfrac{-5}{7}\right)\)\(=\left(\dfrac{5}{7}+\dfrac{-5}{7}\right)+\dfrac{3}{5}\)\(=0+\dfrac{3}{5}=\dfrac{3}{5}\)
b) \(\dfrac{-3}{4}-\dfrac{15}{14}:\dfrac{-5}{7}+\left(-1\right)^2\)\(=\dfrac{-3}{4}-\dfrac{15}{14}:\dfrac{-5}{7}+1\)\(=\dfrac{-3}{4}-\dfrac{-3}{2}+1\)
\(=\dfrac{3}{4}+1\)\(=\dfrac{7}{4}\)