Dạng2: Tìm x trong dấu giá trịtuyệt đốia)|x| = 5
b) |x| < 2
c) |x| = -1
d) |x| =|-5|
e)|x +3| = 0
f) |x-1| = 4
g) |x –5| = 10
h) |x + 1| = -2
i) |x+4| = 5 –(-1)
k)|x –1| = -10 –3
l) |x+2| = 12 + (-3) +|-4|
m) |x+2|-12 = -1
n) 135-|9-x|= 35
o) |2x + 3|=5
Dạng 2:
a) \(\left|x\right|=5\Leftrightarrow\orbr{\begin{cases}x=5\\x=-5\end{cases}}\)
b) \(\left|x\right|< 2\) (vô lí, vì \(\left|x\right|\ge0\forall x\))
c) \(\left|x\right|=-1\) (vô lí, vì \(\left|x\right|\ge0\forall x\))
d) \(\left|x\right|=\left|-5\right|\Leftrightarrow\left|x\right|=5\Leftrightarrow\orbr{\begin{cases}x=5\\x=-5\end{cases}}\)
e) \(\left|x+3\right|=0\Leftrightarrow x+3=0\Leftrightarrow x=-3\)
f) \(\left|x-1\right|=4\Leftrightarrow\orbr{\begin{cases}x-1=4\\x-1=-4\end{cases}\Leftrightarrow\orbr{\begin{cases}x=5\\x=-3\end{cases}}}\)
g) \(\left|x-5\right|=10\Leftrightarrow\orbr{\begin{cases}x-5=10\\x-5=-10\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=15\\x=-5\end{cases}}\)
h) \(\left|x+1\right|=-2\) (vô lí, vì \(\left|x+1\right|\ge0\forall x\))
i) \(\left|x+4\right|=5-\left(-1\right)\Leftrightarrow\left|x+4\right|=6\Leftrightarrow\orbr{\begin{cases}x+4=6\\x+4=-6\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=2\\x=-10\end{cases}}\)
k) \(\left|x-1\right|=-10-3\Leftrightarrow\left|x-1\right|=-13\) (vô lí, vì \(\left|x-1\right|\ge0\forall x\))
l) \(\left|x+2\right|=12+\left(-3\right)+\left|-4\right|\Leftrightarrow\left|x+2\right|=13\Leftrightarrow\orbr{\begin{cases}x+2=13\\x+2=-13\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=11\\x=-15\end{cases}}\)
m) \(\left|x+2\right|-12=-1\Leftrightarrow\left|x+2\right|=11\Leftrightarrow\orbr{\begin{cases}x+2=11\\x+2=-11\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=9\\x=-13\end{cases}}\)
n) \(135-\left|9-x\right|=35\Leftrightarrow\left|9-x\right|=100\Leftrightarrow\orbr{\begin{cases}9-x=100\\9-x=-100\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=-91\\x=109\end{cases}}\)
\(\left|2x+3\right|=5\Leftrightarrow\orbr{\begin{cases}2x+3=5\\2x+3=-5\end{cases}\Leftrightarrow}\orbr{\begin{cases}2x=2\\2x=-8\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=1\\x=-4\end{cases}}\)
Ý cuối là ý o nhé.