Ta có: (-6).(-21)=14x
=> x= \(\dfrac{126}{14}\)=9
Vậy x=9
ĐKXĐ: \(x\ne0\)
Ta có: \(\dfrac{-6}{x}=\dfrac{14}{-21}\)
\(\Leftrightarrow x=\dfrac{\left(-6\right)\cdot\left(-21\right)}{14}=\dfrac{126}{14}=9\)(thỏa ĐK)
Vậy: x=9
Ta có: (-6).(-21)=14x
=> x= \(\dfrac{126}{14}\)=9
Vậy x=9
ĐKXĐ: \(x\ne0\)
Ta có: \(\dfrac{-6}{x}=\dfrac{14}{-21}\)
\(\Leftrightarrow x=\dfrac{\left(-6\right)\cdot\left(-21\right)}{14}=\dfrac{126}{14}=9\)(thỏa ĐK)
Vậy: x=9
Tìm các số nguyên x và y biết \(\dfrac{x}{7}+\dfrac{1}{y}=\dfrac{-1}{14}\) ( với y ≠ 0 )
Tìm x biết \(\dfrac{x}{6}+\dfrac{x}{10}+\dfrac{x}{15}+\dfrac{x}{21}+\dfrac{x}{28}+\dfrac{x}{36}+\dfrac{x}{45}+\dfrac{x}{55}+\dfrac{x}{66}+\dfrac{x}{78}=\dfrac{220}{39}\)
Tìm x, biết:
a) \(\dfrac{3}{4.7}+\dfrac{3}{7.10}+....+\dfrac{3}{x\left(x+3\right)}=\dfrac{9}{38}\)
b) \(\dfrac{1}{21}+\dfrac{1}{28}+\dfrac{1}{36}+...+\dfrac{2}{x\left(x+1\right)}=\dfrac{2}{9}\)
tìm số nguyên x,y biết:
\(\dfrac{1}{x}-\dfrac{1}{y}=\dfrac{1}{2}\)
tìm x biết :
1.\(\dfrac{-5}{6}+\dfrac{8}{3}+\dfrac{-29}{6}\le x\le\dfrac{-1}{2}+2+\dfrac{5}{2}\)
2.\(\left(2,7x-1\dfrac{1}{2}x\right):\dfrac{2}{7}=\dfrac{-21}{4}\)
3.\(\left|2x-\dfrac{3}{4}\right|=1\)
làm hộ mik 3 con này cái
Tìm x biết: \(\dfrac{13}{14}+\dfrac{13}{35}+\dfrac{13}{65}+\dfrac{13}{104}+...+\dfrac{13}{1274}-x+2\dfrac{1}{5}=0\)
Tìm \(x\in N\), biết :
a)\(\dfrac{1}{21}+\dfrac{1}{28}+\dfrac{1}{36}+...+\dfrac{2}{x\left(x+1\right)}=\dfrac{2}{29}\)
Tìm số tự nhiên x, biết:\(\dfrac{1}{3}+\dfrac{1}{6}+\dfrac{1}{10}+...+\dfrac{1}{x\cdot\left(x+1\right):2}=\dfrac{2016}{2018}\)
Tìm các số nguyên ,biết :
a)\(\dfrac{4+x}{x+2}=\dfrac{8}{6}\)
b)\(\dfrac{3}{x-5}=\dfrac{-4}{x+2}\)
c)\(\dfrac{x}{-2}=\dfrac{-8}{x}\)