1/x>1/3,
x≠0,
1/x-1/3>0,
(3-x)/(3x)>0,
3x(3-x)>0,
x(3-x)>0,
3-x=0, x=3,
0<x<3,
x∈(0;3)
(x^2-36)/(x^2+6x)<0,
x^2+6x≠0, x(x+6)≠0, x≠0, x≠-6,
(x-6)(x+6)/(x(x+6))<0,
(x-6)/x<0,
x(x-6)<0,
x-6=0, x=6,
0<x<6,
x∈(0;6);
(x-1)/(x-5)>2,
x-5≠0, x≠5,
(x-1)/(x-5)-2>0,
(x-1-2x+10)/(x-5)>0,
(9-x)/(x-5)>0,
(x-5)(9-x)>0,
(x-5)(x-9)<0,
x-9=0, x=9,
5<x<9,
x∈(5;9);
(x-1)/(x+3)>3,
x+3≠0, x≠-3,
(x-1)/(x+3)-3>0,
(x-1-3x-9)/(x+3)>0,
(-2x-10)/(x+3)>0,
(x+5)/(x+3)<0,
(x+3)(x+5)<0,
x+5=0, x=-5,
-5<x<-3,
x∈(-5;-3)
xy=-12 xy=-12 xy=-12 xy=-12 xy=-12 2x-2x^2=-12
{ ={ ={ ={ ={ ={
(x-2)(y-4)=-8 xy-2y-4x+8=-8 -12-2y-4x+8=-8 -2y-4x=-4 y=2-2x y=2-2x
x^2-x-6=0 x1=3; x2=-2
={ ={
y=2-2x y1=-4; y2=6
x1 и x2 найдены по теореме виета (x1*x2=c; x1+x2=-b => b=nx, c-число)
а1=-11 d=6 a6-? S10-?
Объяснение:
a6=a1+5d
a6=-11+5×6=-11+30=19
S10=(a1+a10/2)×10
a10=a1+9d
a10=-11+9×6=-11+54=43
a10=a1+9d=43
ответ: а6=19 S10=160 ;)