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How do you do substitution in algebra?


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July 12, 2009 4:40AM

Okay, you just asked a VERY long-winded answer question my friend. Alright here is an example question. 2x-1=y+5, y-1=x-5 Solve for x or y, which ever is easiest, first. y-1=x-5 y=x-4 Now plug in y in the other equation. 2x-1=y+5 2x-1=(x-4)+5 2x-1=x+1 2x=x+2 x=2 Now, plug in x in the previous equation that you substituted with first. y=x-4 y=2-4 y=-2 So, the answer to this equation is... x=2, y=-2 I know this might seem complicated but stick with it and don't give up. When you start doing questions you havce to think "I'm gonna get this, easy!" The way you set your mind before doing something will effect the outcome! Good luck! PS--- Here's how to check your answer. Get your two original questions. 2x-1=y+5, y-1=x-5 ... and plug in your answers to see if it checks out right! Here's how. 2x-1=y+5 2(2)-1=-2+5 4-1=3 3=3 Yay, we were right! Now for the other one... y-1=x-5 -2-1=2-5 -3=-3 WooHoo, we were right again! This proves that x=2, y=-2 was indeed the correct answer.