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x^2 + 8x + 15 > 0 solve inequality
(X+5)(X+3)>0
x+5>0 x>-5
X+3>0 x>-3
Why is the equality for X+5>0 x<-5 ? as the answers give?
(X+5)(X+3)>0
x+5>0 x>-5
X+3>0 x>-3
Why is the equality for X+5>0 x<-5 ? as the answers give?
Because you have two possible solutions for (x+5)(x+3)>0
the first one:
x+5>0 ; x>-5
x+3>0 ; x>-3
[tex](-5, +\propto) \cap (-3, +\propto) = (-3, +\propto)[/tex]
and the second
x+5<0 ; x<-5
x+3<0 ; x<-3
[tex](-\propto, -5) \cap (-\propto, -3) = (-\propto, -5) [/tex]
The final solution:
[tex](-\propto, -5) \cup (-3, +\propto)[/tex]
Anyway, this way is much more time-consuming... So you shouldn't use it in future.. There is much easier way...