2.1 Symbols and notations

Suppose that the streets on your way from home to school have speed limits of 35 mph, 25 mph, and 10 mph. In algebra we can let the letter $x$ represent our speed as we travel from home to school. The maximum value of $x$ depends on what section of street we are on. The letter $x$ can assume any one of the various values 35,25,10.

Suppose that in writing a term paper for a geography class we need to specify the height of Mount Kilimanjaro. If we do not happen to know the height of the mountain, we can represent it (at least temporarily) on our paper with the letter $h$ . Later, we look up the height in a reference book and find it to be 5890 meters. The letter $h$ can assume only the one value, 5890, and no others. The value of $h$ is constant .

$a+b$ represents the sum of $a$ and $b$ .

$4+y$ represents the sum of 4 and $y$ .

$8-x$ represents the difference of 8 and $x$ .

$6x$ represents the product of 6 and $x$ .

$ab$ represents the product of $a$ and $b$ .

$h3$ represents the product of $h$ and 3.

$(14.2)a$ represents the product of $14.2$ and $a$ .

$(8)(24)$ represents the product of 8 and 24.

$5\cdot 6(b)$ represents the product of 5,6, and $b$ .

$\frac{6}{x}$ represents the quotient of 6 and $x$ .