I need to figure out the easiest way to solve this and apply the method to every problem

The function is given as,
[tex]f(x_{)=-3x^2-7x}[/tex]It is asked to find the value of the expression,
[tex]f(7)[/tex]This can be obtained by replacing 'x' by 7 in the given expression of the function,
[tex]f(7)=-3(7)^2-7(7)[/tex]Resolve the parenthesis,
[tex]\begin{gathered} f(7)=-3(49)-49 \\ f(7)=-147-49 \end{gathered}[/tex]Simplify the terms further,
[tex]f(7)=-196[/tex]Thus, the value of the expression f(7) is obtained as,
[tex]=-196[/tex]