Hi!
In math, anything that is just grouped together with a bunch of different numbers, operators, or symbols is an expression.
By numbers, I mean your usual 1, 2, 3, 4, 5, 6, 7, 8, 9, etc.
By operators, I mean the operators we use to do calculations with. This will be multiplication, division, addition, and subtraction.
By symbols, I just mean any ol' symbol we can shove in there. This can be pi or stuff such as the actual symbols for our operators. (*, /, +, -). Some more examples would be parentheses and inequality symbols.
So, let's make our own expression.
5 + 9x - (-2x)^2 is in fact an expression! We have numbers, operators, and some symbols.
Also, note that variables are really common in expressions. Don't let them mess you up.
With this new found knowledge, you can answer this question on your own!
Hopefully, this helps! =)