Question

a) |x+1| = |x-1|

b) 4 x |x| = x^2 + 4

Answer 1

phần b là 4x|x| hay 4*|x|

Answer 2

Ta có: |x + 1| = |x - 1|

<=> x + 1 = x - 1

=> x + x =1 - 1

=> 2x = 0

=> x =0

Answer 3

Ta có: 4 x |x| = x² + 4

=> |x| = (x² + 4) : 4

=> |x| = x² : 4 + 1

=> x = 1/4x² + 1

=> x - 1/4x² = 1

=> x.(1 - 1/4x) = 1

=> x . 2/3 = 1

=

Answer 4

a) \(\left|x+1\right|=\left|x-1\right|\Leftrightarrow\hept{\begin{cases}x+1=x-1\\x+1=-\left(x-1\right)=-x+1\end{cases}}\)

+)x+1=x-1

=>x+1-(x-1)=0

=>x+1-x+1=0=>(x-x)+2=0=>0+2=0=>o=-2(vô lí)

+)x+1=-x+1

=>x+1-(-x+1)=0

=>x+1+x-1=0=>2x=0=>x=0

Vậy x=0 thì thỏa mãn PT