помогите пожалуйста с 13 14 17 номерами

Решение на фото

13
1)p/q-q/p=(p-q)/pq
2)1/(p+q)*(p-q)/hq=(p-q)/pq(p+q)
3)(p-q)/pq-(p-q)/(p+q)(pq=(p+pq-pq-q-p+q)/(p+q)pq=
=pq(p-q)/(p+q)pq=(p-q)/(p+q)
4)(p-q)/(p+q):(p-q)/p=(p-q)/(p+q)*p/(p-q)=p/(p+q)
14
1)1/b-1/c=(c-b)/bc
2)(b+c)/bc*(c-b)/bc=(c^4-b^4)/b^4c^4
3)1/a-1/c=(c-a)/ac
4)(c-a)/ac*(a+c)/ac=(c^4-a^4)/a^4c^4
5)(c^4-b^4)/b^4c^4-(c^4-a^4)/a^4c^4=(a^4c^4-a^4b^4-b^4c^4+a^4b^4)/a^4b^4c^4=c^4(a^4-b^4)/a^4b^4c^4(a^4-b^4)/a^4b^4
6)(a^4-b^4)/a^4b^4 :(a+b)/ab=(a-b)(a+b)/a^4b^4c^4 *ab^2/(a+b)=
=(a-b)/ab
17
1)(x+y)/(x+y):(x-y)=(x+y)(x-xy+y)/(x+y) *1/(x-y)=(x-xy+y)/(x-y)
2)(x-xy+y)/(x-y)(x+y)+2y/(x+y)=(x-xy+y+2xy-2y)/(x+y)(x-y)=
=(x+xy-y)/(x-y)(x+y)
3)(x+xy-y)/(x-y)-xy/(x-y)=(x+xy-y-xy)/(x-y)=(x-y)/(x-y)=1