curlylocks Posted January 5, 2012 Share Posted January 5, 2012 We are on Lesson 6 of MUS Algebra 1... Part of the review was using LCM to eliminate fractions and then solve for the unknown. My daughter is just NOT getting "why" one would do this. My question is: is there any reason to teach this?? I've been looking through other math curriculum I have in the house (A Beka and Saxon) and I do not find where either program teaches this. :confused: FWIW, she did show her work and got the correct answer. (she determined common denominators for the 3 fractions and then solved.) Quote Link to comment Share on other sites More sharing options...
curlylocks Posted January 6, 2012 Author Share Posted January 6, 2012 anyone?? :bigear: Quote Link to comment Share on other sites More sharing options...
Dana Posted January 6, 2012 Share Posted January 6, 2012 I'm not familiar with the text. If you're talking about solving linear equations that have fractions, the idea behind clearing the fractions is that then you get an equation that is generally much easier to solve. See here for an example - last example on the page. Quote Link to comment Share on other sites More sharing options...
Mom22ns Posted January 6, 2012 Share Posted January 6, 2012 I'm not familiar with the text. If you're talking about solving linear equations that have fractions, the idea behind clearing the fractions is that then you get an equation that is generally much easier to solve. See here for an example - last example on the page. Yep, this is it. Fractions are an easy way to make a mistake. He is teaching the option of eliminating them to make potentially complicated problems easy. My ds thought it was useless and annoying until he made a couple of fraction mistakes. Then he decided it was useful after all. I think it is worthwhile to know how to do it and why you might want to. Quote Link to comment Share on other sites More sharing options...
Calm37 Posted January 6, 2012 Share Posted January 6, 2012 Got out our books to try to find the trail of where this was first taught since it is in review by lesson 6. Found it on pages 38 (for fractions) and 40 (for decimals) of the student book. I'm thinking he did a few on the video, too. This is a method for simplifying "some" equations. I do think it can be helpful to eliminate the fractions and decimals before solving for the unknown. It is not absolutely necessary to use this at this point in the course. I have done MUS starting with Alpha, though, and I will tell you that it is HIGHLY likely that this method WILL be necessary further on. I have found that Steve very often introduces things early, while they seem simple to understand. I can tell you stories from each level where I thought, certainly they don't have to do it this way, certainly they don't have to do so many! But later, was I ever thankful to see that he had prepared my students well for what was coming down the road. I have come to trust him and just do what he says. :) I would teach it and make sure she knows how to do the simplifying using LCMs for both fractions and decimals. You can go back to the problems from 3C & 3D as a review. As long as you believe she has mastered the method, you can move on. Blessings, Quote Link to comment Share on other sites More sharing options...
Teachin'Mine Posted January 6, 2012 Share Posted January 6, 2012 I think it's great to learn different ways to approach problems. This will give them more options and a greater base to draw on when solving more complicated problems in the future. That said, it's using the common denominator that will be more useful in higher math. : ) Quote Link to comment Share on other sites More sharing options...
curlylocks Posted January 6, 2012 Author Share Posted January 6, 2012 Thanks for all the replies... :) *I* get why they would teach it, but I can't seem to convey to *her* in a way that her light bulb goes on...:001_huh: She just keeps saying, "But I got the correct answer." I really want her to understand this -- and I have to say that she is a really bright kid. She is one that WANTS to understand why, but this particular concept just isn't clicking. I think I need some chocolate...and it's snowing here today so a trip to the store is out of the question. :banghead: Quote Link to comment Share on other sites More sharing options...
Dana Posted January 6, 2012 Share Posted January 6, 2012 Have you showed her a problem that's more complicated? Like the one in the link I gave? If you're doing a problem like 2/3 x = 12, then multiplying by 3 rather than by 3/2 is silly overall. Same with x + 1/4 = 1/3... subtract 1/4; don't multiply by 12 first. Acknowledging that it's a silly way to do the problem on ones that are this simple but showing that it's a technique that'll pay off later may get some understanding. Quote Link to comment Share on other sites More sharing options...
curlylocks Posted January 6, 2012 Author Share Posted January 6, 2012 Have you showed her a problem that's more complicated? Like the one in the link I gave? If you're doing a problem like 2/3 x = 12, then multiplying by 3 rather than by 3/2 is silly overall. Same with x + 1/4 = 1/3... subtract 1/4; don't multiply by 12 first. Acknowledging that it's a silly way to do the problem on ones that are this simple but showing that it's a technique that'll pay off later may get some understanding. Yes...in fact that problem is VERY similar to the problem in her text. :) Although, I like how they worded it better: ", I can first multiply through by the common denominator." (MUS teaches it "multiplying through by the LCM".) I don't know...now her frustration is wearing off on me...maybe dh will take a whack at it tonight. ;) Quote Link to comment Share on other sites More sharing options...
kiana Posted January 6, 2012 Share Posted January 6, 2012 Furthermore, it's setting her up for how to solve problems like 1/x + 1/(x+1) = 3/(x+1). Quote Link to comment Share on other sites More sharing options...
curlylocks Posted January 24, 2012 Author Share Posted January 24, 2012 Well, we hit these problems a few days in a row and suddenly the lightbulb came on. :001_smile: Quote Link to comment Share on other sites More sharing options...
kiana Posted January 24, 2012 Share Posted January 24, 2012 Well, we hit these problems a few days in a row and suddenly the lightbulb came on. :001_smile: Hurrah! Quote Link to comment Share on other sites More sharing options...
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