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Solving Equations by Factoring

Sometimes, one of the pieces is missing... But, it's no big deal.

Check it out:

 

Solve     3y^2 - 5y = 0

Factor: y ( 3y - 5 ) = 0 ... Blobs = 0: y = 0 ( done ) or 3y - 5 = 0 ... Solve: add 5 to both sides of the second equation which gives 3y = 5 which gives y = 5/3

{ 0, 5/3 }

TIP:  It's a very common mistake for students to forget about that
y = 0 answer on a test!  It's because you go on to solve the other guy and get distracted.  So, I always have my students put a big circle around the y = 0 as soon as they get it, so they don't forget about it!  Also, if you do still forget about it, it's circled so that the teacher sees that you knew it was an answer!

YOUR TURN:

Solve  4a^2 + 3a = 0