M^2 -22/13mn+121/169n^2=(m-11/13n)^2
400/441t^2 +40/21nt+n^2=(20/21t+n)^2
(x-2)/(3-x)>0 метод интервалов.
------------2---------------3------------
- + -
x∈(2;3)
Как-то так вроде.
f'(y)=(((x-1)/(x+1))^2)' * ((x-1)/(x+1))'=2((x-1)/(x+1)) * ((x-1)'(x+1)-(x-1)(x+1)')/(x+1)^2=2((x-1)/(x+1)) * ((1-0)(x+1)-(x-1)(1+0))/(x+1)^2=2((x-1)/(x+1)) * (x+1-x+1)/(x+1)^2=2((x-1)/(x+1)) *2/(x+1)^2
1. 3с•(с-2а)
2. 5а в 3•(2а в 4 + 1)
3. (3х-2у)•(а+b)