Question

1. Tìm x, biết:

a) -105 -5.x=(-5)² c)400-4.| 5-x | =( -6)²

b) 2.5²-2.( x+ 1)²=18 d)2.|x-1| -5 = -15

e) |x-12| + |x-13| + |x-14| = |14-x| + |13-x| + 2.|12-x| -8

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Answer 1

a) -105 - 5.x = (-5)^2

=>-105 - 5.x = 25

=> 5.x = -105 - 25

=> 5.x = -130

=> x = -130: 5

=> x = -26

Answer 2

c) 400 -4.|5-x| = (-6)^2

=>400- 4.|5-x| = 36

=> 4.|5-x| = 400-36

=> 4.|5-x| = 364

=> |5-x| = 364:4

=> |5-x| = 91

=> \(\left[\begin{matrix}5-x=91\\5-x=-91\end{matrix}\right.\)

=> \(\left[\begin{matrix}x=5-91\\x=5-\left(-91\right)\end{matrix}\right.\)

^{=> \(\left[\begin{matrix}x=-86\\x=96\end{matrix}\right.\)}

Answer 3

d) 2.|x-1| -5 = -15

=>2.|x-1| = -15+5

=>2.|x-1| = 10

=> |x-1| = 10:2

=> |x-1| = 5

=> \(\left[\begin{matrix}x-1=5\\x-1=-5\end{matrix}\right.\)

=>

Answer 4

d) 2.|x-1| -5 = -15

=>2.|x-1| =-15+5

=>2.|x-1| = 10

=> |x-1| = 10:2

=> |x-1| = 5

=> \(\left[\begin{matrix}x-1=5\\x-1=-5\end{matrix}\right.\)

=> \(\left[\begin{matrix}x=5+1\\x=-5+1\end{matrix}\right.\)

=> \(\left[\begin{matrix}x=6\\x=-4\end{matrix}\right.\)