MATLAB Unable to Store Symbolic Function with Multiple Variables

[poster]

I'm trying to take the definite integral from -1 to 1 of a function with respect to x. The function has variables a, b, c, d, and x, all of which I've defined as syms variables. I'm trying to keep a, b, c, d in my final integral because I'll later be differentiating with respect to each one for an optimization problem. Here's the current code that I have:

    syms f(x);

    syms a b c d;

    f(x)= (exp(x)-a*(1/sqrt(2))-b*(sqrt(3/2)*x)-c((sqrt(45/8))*(x^2-(1/3)))+d((sqrt(175/8))*((x^3)- 

    (3/5)*(x))))^2;

    integral = int(f, x, [-1 1]);

    disp(integral);

Similar code worked when I tried it using only variables x and y for a smaller function. However, when I try this code, I get:

    Error using sym/subsindex (line 825)

    Invalid indexing or function definition. Indexing must follow MATLAB indexing. Function 

    arguments must be symbolic variables, and function body

    must be sym expression.



    Error in sym/subsref (line 870)

                R_tilde = builtin('subsref',L_tilde,Idx);



    Error in HW11 (line 4)

    f(x)= (exp(x)-a*(1/sqrt(2))-b*(sqrt(3/2)*x)-c((sqrt(45/8))*(x^2-(1/3)))+d((sqrt(175/8))*((x^3)-(3/5)*(x))))^2;

I'm pretty new to symbolic functions and syms variables in MATLAB, why is MATLAB rejecting this code? The similar code that I tried that worked was:

    syms f(x);

    syms y;

    f(x) = (x^2) + y;

    integral = int(f, x, [0 3]);

    disp(integral);

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