`1)`
`a) 53.(-49)+49.47`
`= -53.49+49.47`
`= 49.(-53+47)`
`= 49.(-6)`
`=-294`
`b) (-486)-1569+3425-514-(-569)`
`= -486-1569+3425-514+569`
`= (-418-514)+(-1569+569)+3425`
`= -1000-1000+3425`
`=-2000+3425`
`=1425`
`2)`
`a) |x+3|-19=-8`
`<=> |x+3|=-8+19`
`<=> |x+3|=11`
\(⇔\left[ \begin{array}{l}x+3=11\\x+3=-11\end{array} \right.\)
\(⇔\left[ \begin{array}{l}x=11-3\\x=-11-3\end{array} \right.\)
\(⇔\left[ \begin{array}{l}x=8\\x=-14\end{array} \right.\)
- Vậy `x in {8;-14}`
`b) (x+1)^2-1=0`
`<=> (x+1)^2=0+1`
`<=> (x+1)^2=1`
`<=> (x+1)^2=1^2=(-1)^2`
\(⇔\left[ \begin{array}{l}x+1=1\\x+1=-1\end{array} \right.\)
\(⇔\left[ \begin{array}{l}x=1-1\\x=-1-1\end{array} \right.\)
\(⇔\left[ \begin{array}{l}x=0\\x=-2\end{array} \right.\)
- Vậy `x in {0;-2}`
`c) (-x+1)/(-3)=14/(-6)`
`<=> -6.(-x+1)=-3.14`
`<=> 6x-6=-42`
`<=> 6x=-42+6`
`<=> 6x=-36`
`<=> x=-36:6`
`<=> x=-6`
