Tìm x biết a) |x+1/3|-5=7 b) 3(x-2)+2/5=4 17/07/2021 Bởi Daisy Tìm x biết a) |x+1/3|-5=7 b) 3(x-2)+2/5=4
Giải: `a, |x + 1/3| – 5 = 7` `-> |x + 1/3| = 7 + 5` `-> |x + 1/3| = 12` `->` \(\left[ \begin{array}{l}x+\dfrac{1}{3} = 12\\x+\dfrac{1}{3} = -12\end{array} \right.\) `->` \(\left[ \begin{array}{l}x = 12 – \dfrac{1}{3} = \dfrac{36}{3} – \dfrac{1}{3} = \dfrac{35}{3}\\x = – 12 – \dfrac{1}{3} = \dfrac{-36}{3} – \dfrac{1}{3} = \dfrac{-37}{3}\end{array} \right.\) Vậy `x ∈ { 35/3 ; -37/3 }`. `b, 3(x – 2) + 2/5 = 4` `-> 3(x – 2) = 4 – 2/5` `-> 3(x – 2) = 20/5 – 2/5` `-> 3(x – 2) = 18/5` `-> x – 2 = 18/5 : 3` `-> x – 2 = 18/5 . 1/3` `-> x – 2 = 6/5` `-> x = 6/5 + 2` `-> x = 6/5 + 10/5` `-> x = 16/5` Vậy `x = 16/5`. Bình luận
a) `|x+1/3|-5=7` `⇒|x+1/3|=12` $⇒\left[ \begin{array}{l}x+\frac{1}{3}=12\\x+\frac{1}{3}=-12\end{array} \right.$ $⇒\left[ \begin{array}{l}x=\frac{35}{3}\\x=-\frac{37}{3}\end{array} \right.$ Vậy `x=35/3` hoặc `x=-37/3` b) `3(x-2)+2/5=4` `⇔3(x-2)=18/5` `⇔x-2=6/5` `⇔x=16/5` Bình luận
Giải:
`a, |x + 1/3| – 5 = 7`
`-> |x + 1/3| = 7 + 5`
`-> |x + 1/3| = 12`
`->` \(\left[ \begin{array}{l}x+\dfrac{1}{3} = 12\\x+\dfrac{1}{3} = -12\end{array} \right.\)
`->` \(\left[ \begin{array}{l}x = 12 – \dfrac{1}{3} = \dfrac{36}{3} – \dfrac{1}{3} = \dfrac{35}{3}\\x = – 12 – \dfrac{1}{3} = \dfrac{-36}{3} – \dfrac{1}{3} = \dfrac{-37}{3}\end{array} \right.\)
Vậy `x ∈ { 35/3 ; -37/3 }`.
`b, 3(x – 2) + 2/5 = 4`
`-> 3(x – 2) = 4 – 2/5`
`-> 3(x – 2) = 20/5 – 2/5`
`-> 3(x – 2) = 18/5`
`-> x – 2 = 18/5 : 3`
`-> x – 2 = 18/5 . 1/3`
`-> x – 2 = 6/5`
`-> x = 6/5 + 2`
`-> x = 6/5 + 10/5`
`-> x = 16/5`
Vậy `x = 16/5`.
a) `|x+1/3|-5=7`
`⇒|x+1/3|=12`
$⇒\left[ \begin{array}{l}x+\frac{1}{3}=12\\x+\frac{1}{3}=-12\end{array} \right.$
$⇒\left[ \begin{array}{l}x=\frac{35}{3}\\x=-\frac{37}{3}\end{array} \right.$
Vậy `x=35/3` hoặc `x=-37/3`
b) `3(x-2)+2/5=4`
`⇔3(x-2)=18/5`
`⇔x-2=6/5`
`⇔x=16/5`