TABLE OF CONTENTS Shop and other scientific formulas are usually written with one variable on the left side of the equation and all other variables and constants on the right side. When the variable whose value is sought is not isolated, the formula must be rearranged, or transformed. In Chapter 9 we saw how to do this in the simplest case that of a single-variable equation with all other terms constant. Now we consider equations with many variables. The procedure for isolating the variable of interest is the same: relevant operational inverses are applied in succession until the equation or formula is in the desired configuration.
Variables represent physical entities that can be quantified, or given numerical values. Some common variables in technical mathematics are r, d, t, s, ?, and v, as well as C, I, P, R, ?, ?, and ?. Equations composed of this kind of variable are called literal equations. For example, the distance formula, d = rt, is a literal equation describing distance traveled, d, as a function of rate, r, and time, t. Another example of a literal equation is the well-known formula for determining circumference of a circle, C = 2 ?r.
d = rt is a linear equation in which the slope is r and the y-intercept is 0.
