2(b-a)
1/2a
(a-b)/((a-b)(a+b))
(7*a*b+3)/(2*b)
(35*(b-c)*(b-c))/((45-b)(a-4))
4*a*b-sqrt(a*a)
sqrt(4*b*sqrt(b-a))
cos(x*x*x)
tg(sqrt(x*x))
sqrt(sin(x*x))
