What is the solution of mc016-1.jpg? \frac{x^2-1}{x^2+5x+4}< 0

( x² - 1 ) / ( x² + 5 x + 4 ) < 0
x² + 5 x + 4 = x² + 4 x + x + 4 =  x ( x + 4 ) + ( x + 4 ) = ( x + 4 ) ( x + 1 )
Therefore:
( x - 1 ) ( x + 1 ) / ( x + 4 ) ( x + 1 ) < 0
( x -1 ) / ( x + 4 ) < 0
1.
x - 1 > 0  and x + 4 < 0
x  > 1  and  x < - 4       ( not possible ) 
2. 
x - 1 < 0 and x + 4 > 0
x < 1  and x > - 4 
 x ∈ ( - 4, 1 ).