A1=1,3-5,7=-4,4 a2=1,3-11,4=-10,1 d=a2-a1=-10,1+4,4=-5,7
S15=(2a1+14d)*15/2=(-8,8-79,8)*15/2=(-88,6)*15/2=-44,3*15=-664,5
(9-x²)/(x-2)>0
(3-x)(3+x)/(x-2)>0
x=3 x=-3 x=2
_ + _ +
--------------(-3)---------------(2)--------------(3)-----------------
x∈(-3;2) U (3;∞)