GMAT On Demand: The Basics of Independent and Dependent Equations

by Knewton, Mar 9, 2011

In this Knewton video, Jess and Rich cover the basics of independent and dependent equations on Data Sufficiency questions. Here are some of the concepts you need to keep an eye on:

• Systems of equations are dependent if one equation can be formed by manipulating and/or combining the others.
• If no manipulation/combination can create dependent equations, the equations are said to be independent.
• We need n independent equations to solve for a system with n variables.
• Dependent equations give us redundant information, so they don't help us solve for all variables.
• If we try to solve a system with dependent equations, we will find that doing so is impossible. We will end up with an identity.

Check out the video for more detailed explanations and examples! For more Data Sufficiency tips, be sure to check out past installments of this quant strategy lesson:

• Don't Solve Data Sufficiency Problems
• Testing Cases in Data Sufficiency
• How to Simplify Data Sufficiency Problems
• Three Classic DS Problems Involving Systems of Equations

And for even more on-demand video help, check out these sessions on Critical Reasoning, Intro to Quant, and Sentence Correction.