Density is the mass per unit volume. By direct translation, ρ = m/v
It means; Density equals pressure
It is a more complicated mathematical expression.
Yes, a mathematical expression can have no variables, but such an expression is usually not very useful. An example of a valid expression without variables is: 1+1=2
It means "a Mathematical Expression".
Average speed can be represented by the mathematical expression "distance x time."
Density is measured as mass per unit volume. The expression for density is: Density = mass/volume.
EQUATION
It is called "to evaluate" the expression.
A mathematical expression is a collection of numbers and variables along with mathematical operators - other than equalities or inequalities.
Any "expression" that represents a numeric value. Example: 2+2=4 or x+7=10. Actually the examples above are equations, not expressions. Expressions do not have = signs. 7a and 4x are examples.
formula
a formula