16
{3x+5>0⇒x>-5/3
{x²+1>0⇒x∈R
{3x+5x²-3x-4>0⇒x<-1 U x>4
x1+x2=3 U x1*x2=-4⇒x1=-1 U x2=4
x∈(-5/3;-1) U (4;∞)
17
{x+3>0⇒x>-3
{x>0
{x+2>0⇒x>-2
{lg(x²+3x)(-1+√3)
D=4+8=12
x1=(-2-2√3)/2=-1-√2 U x2=(-3+2√3)/2=-1+√2
x∈(-1+√2;∞)
18
{(x-√5)(x+√5)>0⇒x<-√ U x>√5
log(4)(x²-5)<1<br>x²-5<4<br>x²-9<0<br>(x-3)(x+3)<0<br>-3x∈(-3;-√5) U (√5;3)