2c/(b+c) -(b-c)²/b(b/(c-b)² + b/(b² -c²)) = 2c/(b+c) -(b-c)²/b(b/(b-c)² + b/(b-c)(b+c)) =
=2c/(b+c) - 1 - (b-c)(b+c)= =2c/(b+c) - (b+c)/(b+c) -(b-c)(b+c)=(2c-b-c-b +c)/(b+c)= =2(c-b)/(c+b) .
x----X
(7a+14b)/(a² -b²)* (a²-2ab+b²)/(5a +10b)=7(a+2b)/((a-b)(a+b))*(a-b)²/5(a +2b) =
=7*(a-b)/(5(a+b)) =5(1,45-0,55)/5(1,45+0,55) =5*0,9/10 =0,45.