Please help with all three This is my last question

QUESTION 1 Find the fourth derivative of f(x) = sin(x). A(4 ) = ? QUESTION 2 Find all intervals where f(x) = x5 - 30x is concave downward. f(x) is concave downward on and **Write intervals in increasing order (interval with smaller x-value first blank). For negative infinity, write "-inf". For infinity, write "inf". QUESTION 3 Find all inflection points for the function f(x) = x5 - 30x3. Inflection points for f(x) are , and Write points in increasing order of x-values (smallest x-value first, largest x-value last)