(1/a)+(1/b)=1/t ⇒(a+b)/ab = 1/t ⇒ t=ab/(a+b)
3 < a < 5
3+12 < a+b < 5+2
1/17 < 1/(a+b) < 1/15
36=3·12 < ab < 5*12=60
2 целых 2/17 = 36/17< ab/(a+b)< 60/15=4
2 целых 2/17 < t < 4
[3;4]
(1/a)+(1/b)=1/t ⇒(a+b)/ab = 1/t ⇒ t=ab/(a+b)
3 < a < 5
3+12 < a+b < 5+2
1/17 < 1/(a+b) < 1/15
36=3·12 < ab < 5*12=60
2 целых 2/17 = 36/17< ab/(a+b)< 60/15=4
2 целых 2/17 < t < 4
[3;4]