Question

x²+8x+15>0
x²-4x-5>0​

Answer 1

x²+8x+15>0

x²+8x+15=0, a=1,b=8, c= 15

D=b²-4ac=8²-4×1×15=64-60=4

x1=-b-√D/2 = -8-√4/2=-8-2/2=-10:2=-5

x2=-b+√D /2=-8+√4/2=-8+2/2=-3