(х+5)^2-x^2=x-2

(x+5-x)(x+5+x)=x-2

5(2x+5)=x-2

10x+25=x-2

10x-x=-2-25

9x=-27

x=-3

(6-x)^2-16=x^2-2x

36-12x+x^2-16=x^2-2x

-10x=-20

x=2

(x-5)(x+5)-x(x+3)<6

x^2-25-x^2-3x<6

-3x<31

x>-31/3

x∈(-31/3;+∞)