Calculus 1. Second derivatives?

Question

Find the second derivative of the functions:

1) (x^4+9)/(x²)

Answer choices:
A)d²y/d²x= 2-(54/x^4)
B)d²y/d²x= 2+(54/x^4)
C)d²y/d²x=1+(54/x^4)
D)d²y/d²x= 2x-(18/x^3)

2) s= (t^6+5t+7)/(t²)

Answer choices:
A)d²s/dt²= 12t^4 + (10/t) + (42/t²)
B)d²s/dt²= 4t² + (5/t^3) - (14/t^4)
C)d²s/dt²= 4t^3 - (5/t²) - (14/t^3)
D)d²s/dt²= 12t² + (10/t^3) + (42/t^4)

Answer 1

1) The function

Apply deriative on each side with respect of x.

The quotient rule in deriatives

Apply the formulae

Product of powers property

Again deriative on each side with respect of x .

Option B is correct choice.

Answer 2

2) The function

Apply deriative on each side with respect of t.

The quotient rule in deriatives

Apply the formulae

Product of powers property

Again deriative on each side with respect of t .

Option D is correct answer.