TASC For Dummies
Not all equations that you'll deal with on the TASC Math exam will be in single variables. There are common formulas that you may need to rearrange to find a certain variable or combination of variables.

The following examples illustrate how to isolate a particular variable given an equation or formula.

Example 1:

In this example, the formula is how force is calculated: Force equals mass times acceleration. As indicated, you're solving for mass, m.

F = ma

To isolate m, notice that it's being multiplied by a. This means you must divide by a on both sides.

Example 2:

This formula is used to calculate the volume of a cone given its height and radius. As indicated, you're solving for the radius, r.

First, multiply by 3 to "get rid of" the fraction.

Don't be scared of pi; it's just a number that can be divided.

Lastly, take the square root of both sides to isolate r.

Example 3:

Because you're looking for xy, you need to simplify both sides and get any terms with xy onto the same side.

Distribute 4x.

Notice that xy is on one side, and all that's left is to divide by 2.

This means that the solution to this problem is 4 – 10x.

About the book authors:

Stuart Donnelly, PhD, was awarded a PhD in mathematics from Oxford University. He has prepared students for the TASC test and GED Test for the past two decades.

Stuart Donnelly, PhD, earned his doctorate in mathe-matics from Oxford University at the age of 25. Since then, he has established successful tutoring services in both Hong Kong and the United States and is considered by leading educators to be one of the most experienced and qualified private tutors in the country.

Stuart Donnelly, PhD, was awarded a PhD in mathematics from Oxford University. He has prepared students for the TASC test and GED Test for the past two decades.

Stuart Donnelly, PhD, was awarded a PhD in mathematics from Oxford University. He has prepared students for the TASC test and GED Test for the past two decades.

Sandra Luna McCune, PhD, is professor emeritus and a former Regents professor at Stephen F. Austin State University. She's now a full-time author. Shannon Reed, MA, MFA, is a visiting lecturer at the University of Pittsburgh, where she teaches composition, creative writing, and business writing.

Stuart Donnelly, PhD, was awarded a PhD in mathematics from Oxford University. He has prepared students for the TASC test and GED Test for the past two decades.