If x equals negative 2 and y equals the square root of 12, then begin expression . . 2 times the quantity . . 3 times x raised to the third power, plus 2 times y raised to the second power . . end expression . . equals

I will assume that you want help in writing the expression since these do not end with equal signs.

2 * ((3 * x)^3) + 2(y^2)  You simply replace the x with -2 and y with sqrt (12)
2 * (-2)^3 + 2 (12)
-16 + 24
8

Variables, letters, ordinary numbers and operators are used to represent numbers in an algebraic expression, like what we commonly see in algebra. A mathematical expression with a variable is 2x + 3 is an example of a mathematical expression. A coefficient, which is a number that is multiplied by the variable is a requirement for all variables.