Даю 90 баллов! номер 49(б, г); 50(б); 51(б, г)

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49 б)2/a-7/b=(2b-7a)/ab г) c/ab+a/cd=(c²d+a²b)/abcd 50б 5/a+(3a-5)/(a+1)=(5a+5+3a²-5a)/a(a+1)=(3a²+5)/[a(a+1)] 51 б)(a+1)/(a-1)+(a-1)/(a+1)=(a²+2a+1+a²-2a+1)/(a²-1)=(2a²+2)/(a²-1) (a+1)/(a-1)-(a-1)/(a+1)=(a²+2a+1-a²+2a-1)/(a²-1)=4a/(a²-1) г)m/(m+4)+m/(m-4)=[m(m-4+m+4)]/(m²-16)=2m²/(m²-16) m/(m+4)-m/(m-4)=[m(m-4-m-4)]/(m²-16)=-8m/(m²-16)=8m/(16-m²)