8 Â 5/648
Step-by-step explanation:
y = 5x ^ -3 + 4x^2
dy /dx = 5 * -3 x^ -4 + 4 * 2x ^ 1
      = -15 x ^ -4 + 8x
Now take the second derivative
dy^2/ dx^2 = -15 Â * -4 x^-5 +8
          = 60 x^ -5 +8
          = 60 /x^5  +8
Evaluate at x = 6
          = 60 / 6^5  +8
          60/7776 +8
          5/648 + 8
         8  5/648