Working Technique to SOLVE Systems of Equations: SUBSTITUTION and ELIMINATION

Sometimes equations have more than one variable. Learn how to solve equations with 2 variables in this video! The two main methods are Substitution and Elimination! Find out what they are in this video! If you like this video leave a LIKE and, if you haven't already, SUBSCRIBE!! Chapters: 0:00 Introduction 0:32 Substitution Introduction 2:26 Common substitution error! 2:46 Elimination Introduction 4:25 Practice 4:45 Solution with Substitution 6:43 Solution with Elimination 7:43 Recap ⬇⬇⬇ SOLUTIONS to the PRACTICE questions!! ⬇⬇⬇ 1. Solve for a and b a + b = 10 2a - 3 = 9 The correct answers: a = 6 and *b = 4*. A quick method to solve this is by using the second equation, 2a - 3 = 9 we can isolate a by adding 3 to both sides and then dividing by 2. 2a - 3 = 9 2a - 3 +3 = 9 +3 2a = 12 a = 6 Now we can just use the value for a and solve for b 6 + b = 10 b = 10 -6 b = 4 2. Solve for p and q 2p + 3q = 9 p - 3q = 0 The correct answers: p = 3 and q = 1 We can use elimination and combine these two equations together. This gets us: 3p = 9. Now just divide both sides by 3, and we find p = 3 We can now use this value and substitute it in one of the equations to solve for q USING THE FIRST EQUATION: 2p + 3q = 9 2( 3 ) + 3q = 9 6 + 3q = 9 3q = 3 q = 1 USING THE SECOND EQUATION: p - 3q = 0 3 - 3q = 0 -3q = -3 q = 1