TS EAMCET 11-Sep-2020 Shift 2 Solved Paper

Given that, An={(n+1)k∣k∈N}
If n=1,A1={2k∣k∈N}
for, k=1,2,3...A1={2,4,6,8,...}
If ‌‌n=2,A2={3k∣k∈N}
for k=1,2,3,...‌‌A2={3,6,9,...}
If n=3,A3={4k∣k∈N}
for k=1,2,3,...A3={4,8,12,...}
Now, X=⋃n∈NAn or X=A1∪A2∪A3...
or ‌‌X={2,3,4,5,6,...}
Here, f:X→N and f(x)=x‌∀x∈X
∵f(x) is linear function i.e., it is one-one function but there is no value of x in domain where f(x)=1
∴f(x) is not onto function.