Đáp án:
Giải thích các bước giải:
Bài 1:
`a)x(x+7)=0`
`→` \(\left[ \begin{array}{l}x=0\\x+7=0\end{array} \right.\)
`→` \(\left[ \begin{array}{l}x=0\\x=-7\end{array} \right.\)
Vậy `x∈{0;-7}`
`b)(x+12)(x-3)=0`
`->` \(\left[ \begin{array}{l}x+12=0\\x-3=0\end{array} \right.\)
`->` \(\left[ \begin{array}{l}x=-12\\x=3\end{array} \right.\)
Vậy `x∈{-12;3}`
`c)(-x+5)(3-x)=0`
`->` \(\left[ \begin{array}{l}-x+5=0\\3-x=0\end{array} \right.\)
`->` \(\left[ \begin{array}{l}x=5\\x=3\end{array} \right.\)
Vậy `x∈{5;3}`
`d)x(x+2)(7-x)=0`
`->` \(\left[ \begin{array}{l}x=0\\x+2=0\\7-x=0\end{array} \right.\)
`->` \(\left[ \begin{array}{l}x=0\\x=-2\\x=7\end{array} \right.\)
Vậy `x∈{0;-2;7}`
`e)(x-1)(x+2)(-x-3)=0`
`->` \(\left[ \begin{array}{l}x-1=0\\x+2=0\\-x-3=0\end{array} \right.\)
`->` \(\left[ \begin{array}{l}x=1\\x=-2\\x=-3\end{array} \right.\)
Vậy `x∈{1;-2;-3}`
Bài 2:
`a)(2x-5)+17=6`
`->2x-5=-11`
`->2x=-6`
`->x=-3`
Vậy `x=-3`
`b)10-2(4-2x)=-4`
`->10-8+4x=-4`
`->2+4x=-4`
`->4x=-6`
`->x=-3/2`
Vậy `x=-3/2`
`c)-12+3(-x+7)=-18`
`->-12-3x+21=-18`
`->9-3x=-18`
`->3x=9-(-18)`
`->3x=27`
`->x=9`
Vậy `x=9`
`d)24:(3x-2)=-3`
`->3x-2=-8`
`->3x=-6`
`->x=-2`
Vậy `x=-2`
`e)-45:(-3-2x)=3`
`->-3-2x=-15`
`->2x=(-3)-(-15)`
`->2x=12`
`->x=6`
Vậy `x=6`
