(Solved): The following data are for a certain function (1.1) Use the Lagrange interpolating polynomial of de ...

The following data are for a certain function (1.1) Use the Lagrange interpolating polynomial of degree three to determine the approximation of the underlying function and the approximate value $f(0.18)$. (1.2) Find the error bound for the Lagrange polynomial. (1.2) The data was generated using the function, $f(x)=x^2\cos x-3x$. Find the actual error in the approximation obtained using the method in (1.1) above.