Can you please tell me how to fix the error in my script box MATLAB

My Solutions Understanding Substitution (Indefinite Integral) Recall the Chain Rule for derivatives: (ng(x)))'s/Tg(x))"g(x) Substitution is nothing more than rewriting this rule in Integral form by letting u g( x) f'(g(a) g'(x) da -J f'(u) du -f (u) C -f (g(x)) +C Note that, ifus g(x ), then du = g x ) * dx using differential notation, so d: du / g '( x ) Use this idea and the strategy outlined in the Solution Template to evaluate 3 Then use int to evaluate the integral directly to compare answers. Refer to this page to help with making your substitutions if needed: http://www.mathworks.com/help/symbolic/subs.html Your Script C Reset B MATLAB Documentation Save 11 syms x uc 2 f- (-1/3) * exp(-3%); 3 u_of_x- (1/3)* (x3) 4 du diff (u of_x); 7 F int(f_of_u)+C 8 F-subs(F_of_u,u of x,u); 9 Falt int (x2 exp-(x3))+C Run Script Assessment: Run Pretest Submit Pretest results are not submitted for grading. To run all the tests and submit the results for grading, click Submit. Test that the two methods yield the same answer (Pretest) Undefined function or variable 'F_of_u Error in solution (line 8) F-subs(F_of_u,u_of_x,u)