1. ((a+-b))*((a+b)+(a-b))*(1/a+1/b) = (a+b-a+b)*(a+b+a-b)*(1/a+1/b) = 2a*2b*(a+b)/ab = 4a+4b = 4(a+b)
2. (1,8·3)(10-3·105)=5,4
3. -164
4. 3,3
5. 6
6. а
7. б
