I think I have the correct answers for the following problems. For anyone who has the time I would appreciate it if you could tell me if I am correct/incorrect. Thank you.

Question

1). Differentiate �ã(x)sin x = (2xcosx+sinx)/2�ã(x)

2). Differentiate 2t/(4+t^2) = (8-2t^2)/(4+t^2)^2

3). Differentiate (1-secx)/(tanx) = secx(-tan^2x + sec^2x)/(tanx)^2

4). Find equation of tangent line
y=(1+x)(cos x)

tangent line = y= x+1

5). If f(3)=4 g(3)=2 f'(3)=-6 g'(3)=5
A).(f+g)(3) = 6
B).(fg)(3) = 8
C).(f/g)(3)= -8

Note: �ã(x) is supposed to be square root of x.