1.1 к общему знаменателю
1.2с общими знаменателями.
3.
б)=(3b-c)/14 - (b-c)/7=(3b-c)/14 - 2(b-c)/14=
=(3b-c-2b-2c)/14=(b-3c)/14.
в)=1/а^2 +(а-2)/а=1/а^2 +а(а-2)/а^2=
=(1+а^2-2а)/а^2.
г)=(b-a)/ab -(a-b)/b^2=( b(b-a)-a(a-b))/ab^2=
=(b^2-ab-a^2+ab)/ab^2=(b^2-a^2)/ab^2.
4.
б)=(х-1)/(3х-12) - (х-3)/(2х-8)=
=(х-1)/3(х-4) - (х-3)/2(х-4)=
=((х-1)×2 - (х-3)×3)/6(х-4) =
=(2х-2-3х+9)/6(х-4)=
=(7-х)/6(х-4).
в)=(3х^2-8у^2)/х(х-2у) - (3ху-х^2)/у(х-2у)=
=(у(3х^2-8у^2)-х(3ху-х^2))/(ух(х-2у))=
=(2х^2у-8у^3-3х^2у+х^3)/ху(х-2у)=
=(-х^2у-8у^3+х^3)/ху(х-2у).
5.
б)5х +1/х=(5х^2+1)/х
в)=(3х(2х-3)+3+4х-4х^2+2х-3)/(2х-3)=
=(6х^2-9х+3+4х-4х^2+2х-3)/(2х-3)=
=(2х^2-3х)/(2х-3)=(х(2х-3))/(2х-3)=х.
7.
б)=2/(2-а)^2 +3/(а-2)^2=2/(2-а)^2 - 3/(2-а)^2=
=- 1/(2-а)^2.
8.
б)=4n/(h(h-l)) -5h/(n(h-l))=
=(4n^2-5h^2)/(nh(h-l))
в)3(5+l)/(4(l^2-6l+9)) -2(6-l)/(3(l-3))=
=3(5+l)/(4(l-3)^2) - 2(6-l)/(3(l-3))=
=(9(5+l)-8(6-l)(l-3))/12(l-3)^2=
=(45+9l-8(6l-18-l^2+3l))/12(l-3)^2=
=(45+9l-8(9l-18-l^2))/12(l-3)^2=
=(45+9l-72l+144+8l^2)/12(l-3)^2=
=(189-63l+8l^2)/12(l-3).
больше нет времени