I'll help ya
To find where a function is concave up or concave down, you need to calculate the second derivative denoted . In this case, they gave you it:
Now, once you calculate the second derivative, you look for the intervals where it is positive or negative. Where the second derivative f''(x) is positive, then the graph of f(x) is concave up. Where it is negative, the graph of f(x) is concave down .
Now find those intervals