f(x)=0.2x^4+0.3x^3-0.8x^2+5

1. Find the derivative of f(x). (differentiate it, or find d(f(x))/dx)
2. At maximum and minimum points, the derivative has a value of zero. So, set the derivative to zero, and solve for the values of x. You should have 3 answers.

**You'll have to use