`(11-x):(-5)=15`
`=> 11-x=-75`
`=> x=86`
Vậy `x = 86`
`((2x+3)^2022) . (-7x+84)=0`
`=> (2x+3)^2022 = 0` hoặc `-7x + 84 = 0`
`=> 2x+3=0` hoặc `-7x = -84`
`=> x = -3/2` hoặc `x = 12`
Vậy `x = -3/2` hoặc `x = 12`
`(x-3)(x+1) < 0`
Ta có: `x - 3 < x + 1`
nên: `x - 3 < 0` và `x + 1 > 0`
`=> x < 3 và x > -1`
`=> -1 < x < 3`
Vậy `-1 <x < 3`
#\(N\)
`a, (11-x)`\(\div\)`(-5)=15`
`11-x=15.-5`
`11-x=-75`
`x=11-(-75)`
`x=11+75=86`
`b, (2x-3)^2022.(-7x+84)=0`
`=>`\(\left\{{}\begin{matrix}\left(2x-3\right)^{2022}=0\\\left(-7x+84\right)=0\end{matrix}\right.\)
`=>` \(\left\{{}\begin{matrix}2x-3=0\\-7x+84=0\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}2x=3+0\\-7x=0-84\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}2x=3\\-7x=-84\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}x=3\div2\\x=-84\div-7\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}x=\dfrac{3}{2}\\x=12\end{matrix}\right.\)
`c, (x-3) (x+1) <0`
`-> (x-3) < x+1`
`-> (x-3)<0 , (x+1)>0`
`-> x < 3 , x> (-1)`
`-> 3 > x > -1`
