u/InternationalStage97

Hi,

So I have trouble understanding how to split up inequalities. In the first pic taking b+c<a+b and taking b+c<c is okay and the answer comes out as D.

But in the second question when I try to take 1<4/√(a+1) and 1 < √(a+1)/2 the answer comes out as 3<a<15 which is wrong (correct ans: 3<a<7).

Why can I take the last element and compare it to the first element in one question but not the other? I can just accept that this is how it is solved but It bugs me to not fully understand something.

Any help would be appreciated.

BTW this is NOT a test. Just practice questions.