Ответ:

Объяснение

1.4/b-5 + 1/b=(4*b+1*(b-5))/b(b-5)=(4b+b-5)/b(b-5)=5(b-1)/b(b-5)

2.x/y - c/(x+y)=(x(x+y)-c*y)/y(x+y)=(x^2+xy-cy)/y(x+y)

3.3/(a+b)+5/(a-b)=(3(a-b)+5(a+b))/(a+b)(a-b)=(3a-3b+5a+5b)c/c+3 /a^2-b^2=

8a+2b/a^2-b^2=2(4a+b)/(a-b)(a+b)

4.c/c+3 - c/c-2=c(c-2)-c(c+3)/(c+3)(c-2)=c^2-2c-c^2-3c/(c+3)(c-2)=

-(2c+3c)/(c+3)(c-2)

5.= -y^2+2y-1+y^2-7y=-(5y+1) при y=-2/3 -(5*(-2/3)+1)=-(-10/3+1)=-(-7/3)=7/3