It's a number placed before & multiplying another quantity, such as 5 in the expression 5x
The positive 
square root of the quantity x squared + y squared, is not equal to x + y .... A 
solution of such an equation is an ordered pair of numbers x comma y that makes 
the... [DOC] [TLE] Functions, Expressions, and Equations - Wiley [PAR] the value of one quantity determines the value of another, we say the second 
quantity is a function .... To evaluate a function at an expression, such as a  2, it 
is helpful to ... (a) This is the average number of days a house stays on the market 
before being sold ... (a) The input, 3500, is the area of the walls, so its units are ft2
.