Question

(10-x)^2+(x+10)(10-x)<0

Answer 1

(10-x)^2+(x+10)(10-x)<0

100-20x+x^2+(10+x)(10-x)<0

100-20x+x^2+100-x^2<0

200-20x<0

-20x<-200

x>10

Answer 2

(10-x)^2+(x+10)(10-x)<0,

вынести за скобки (10-х),

(10-х)(10-х+х+10)<0,

(10-х)20<0,

10-х<0,

-х<-10,

х>10

х€(10; +беск)