Question

tìm số hữu tỉ x biết \(\left|x-3.5\right|\)- 3.5 = 4

Answer 1

\(\left|x-3.5\right|-3.5=4\)

⇒\(\left|x-15\right|-15=4\)

⇒\(\left|x-15\right|=4+15\)

⇒\(\left|x-15\right|=19\)

TH1: \(x-15=19\) TH2:\(x-15=-19\)

\(x=19+15\) \(x=-19+15\)

\(x=34\) \(x=-4\)

⇒x=\(\left[{}\begin{matrix}34\\-4\end{matrix}\right.\)

Answer 2

\(\left|x-3,5\right|=4+3,5\)

\(\left|x-3,5\right|\)= 7,5

*TH1: x - 3,5<0(=)x<3,5

(=)x - 3,5=-7,5

x=-7,5+3,5

x=-4(TMĐK)

*TH2: x - 3,5\(\ge\)0

x - 3,5=7,5

x=7,5+3,5

x=11(TMĐK)

Answer 3

3.5 hay 3,5 p??????????Phạm Phương Hồng

Answer 4

\(\left|x-3,5\right|-3,5=4\)

\(\Rightarrow\left|x-3,5\right|=4+3,5=7,5\)

\(\Rightarrow\left[{}\begin{matrix}x-3,5=7,5\\x-3,5=-\left(7,5\right)\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}x=11\\x=-4\end{matrix}\right.\) (thỏa mãn đk )

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