\(a,\left(x+2\right)^{10}+\left(x+2\right)^8=0\\ \Leftrightarrow\left(x+2\right)^8\left[\left(x+2\right)^2+1\right]=0\\ \Leftrightarrow\left[{}\begin{matrix}\left(x+2\right)^8=0\\\left(x+2\right)^2+1=0\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x+2=0\\\left(x+2\right)^2=-1\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x=-2\\x\in\varnothing\end{matrix}\right.\\ b,\left(x+3\right)^{10}-\left(x+3\right)^8=0\\ \Leftrightarrow\left(x+3\right)^8\left[\left(x+3\right)^2-1\right]=0\\ \Leftrightarrow\left[{}\begin{matrix}\left(x+3\right)^8=0\\\left(x+3\right)^2-1=0\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x+3=0\\\left(x+3\right)^2=1\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x=-3\\x+3=1\\x+3=-1\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=-3\\x=-2\\x=-4\end{matrix}\right.\)

Đáp án D

\(\dfrac{x+8}{12}+\dfrac{x+9}{11}+\dfrac{x+10}{10}+3=0\\ \Leftrightarrow\dfrac{x+8}{12}+1+\dfrac{x+9}{11}+1+\dfrac{x+10}{10}+1=0\\ \Leftrightarrow\dfrac{x+20}{12}+\dfrac{x+20}{11}+\dfrac{x+20}{10}=0\\ \Leftrightarrow\left(x+20\right)\left(\dfrac{1}{12}+\dfrac{1}{11}+\dfrac{1}{10}\right)=0\\ \Leftrightarrow x+20=0\Leftrightarrow x=-20\\ KL:...\)

`<=>((x+8)/12+1)+((x+9)/11+1)+((x+10)/10+1)=0`

`<=>(x+20)/12+(x+20)/11+(x+20)/10=0`

`<=>(x+20)(1/12+1/11+1/10)=0`

Vì `1/12+1/11+1/10 ≠ 0`

`=>x+20=0`

`=>x=0-20`

`=>x=-20`

|x+8|=10

Vì đây là giá trị tuyệt đối suy ra:

x+8=10;x=10-8=2

x+8=-10;x=-10-8=-18

Vậy x=2;-18

| x + 8 | = 10

\(\Rightarrow\)x+8=10

x =10-8

x = 2

hoặc x+8=10

x = - 10 - 8

x = - (10+8)

x = -18

Vậy x \(\in\) { 2; -18 }

\(\dfrac{x}{-8}=\dfrac{-15}{10}\\ \Rightarrow10x=\left(-8\right)\left(-15\right)=120\\ \Rightarrow x=12\)

Vậy x = 12

x=\(\dfrac{-15}{10}.\left(-8\right)\)=12

\(\dfrac{x}{-8}=-\dfrac{15}{10}\)

\(=>x=\dfrac{-8\cdot-15}{10}\)

\(x=12\)

Vậy x =12

` (3/4 +x) xx 50/100 = 8/10`

`( 3/4 + x) xx 1/2 = 4/5`

` 3/4 + x = 4/5 : 1/2`

` 3/4 + x = 4/5 xx2`

` 3/4 + x = 8/5`

` x = 8/5 - 3/4`

` x = 17/20`

Tìm x, biết:

( 3/4 + x ) x 50/100 = 8/10

( 3/4 + x ) = 8/10 : 50/100

( 3/4 + x ) = 8/5

x = 8/5 - 3/4

x = 17/20.

=>x+3/4=4/5:1/2=4/5x2=8/5

=>x=8/5-3/4=32/20-15/20=17/20