Simple Algebraic EquationsDate: 5/26/96 at 15:58:8 From: Anonymous Subject: Simple Algebraic Equations I know this is a pretty broad topic but I just can't seem to understand how you can logically say that 10 + 5x = 110 and have x equals -30 when logically x should equal 20. I just don't understand. Lost, Anacas Date: 5/28/96 at 0:7:25 From: Doctor Ken Subject: Re: Simple Algebraic Equations Hello! You're absolutely right, in the equation 10 + 5x = 110, the correct answer for x is 20. Whenever you solve an equation, you should be able to take your answer and plug it back into the equation and have it make sense. So, if you've got the equation 5x = 80 and you solve it and get x = 3, then you know something isn't right when you plug in 3 for x and get 5 x 3 = 80, which (last time I checked) is way off. So how can we "show" that the solution to your equation is x = 20? Well, here's one way: 10 + 5x = 110 subtract 10 from both sides 5x = 100 divide both sides by 5 x = 20 Does that make sense? -Doctor Ken, The Math Forum Check out our web site! http://mathforum.org/dr.math/ |
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