Homework Help: Simple integration for Work

1. The problem statement, all variables and given/known data
An applied force varies with position according to F = k₁xⁿ - k₂, where n = 3, k₁ = 8.3 N/m³, and k₂ = 87 N. How much work is done by this force on an object that moves from x_i = 6.47 m to x_f = 14.9 m? Answer in units of kJ.



2. Relevant equations

W = k₁ x⁴/4 ]from the integral of x₁ to x2
- k₂x]from x₁to x₂
3. The attempt at a solution
I plugged in everything, and I got 96.778 at first, then I thought I should use x3³/3, then I got 6.543478 kJ.
I got both them wrong, did I do the calculation wrong? Please help, thanks. :D



SOLVED

 

I still didn't get that answer. :(

 

I found my mistake, thank you very much.