Multiplying fractions provides an interesting challenge. Put some mixed number into the situation and you could be facing a real bear.
Here’s one way to work the problem by converting it to mixed numbers:
Or you can use the handing dandy distributive property (or as some might recognize it – FOIL):
Here’s one more for fun:
Thanks to NapNinja4 on MyMathForum for this question.
This isn’t something you do everyday. Therefore it would be helpful to know how to remember it long term.
The mixed number really means .
Notice the PLUS sign? That’s the big key to doing this.
This video shows the long expanded way that most people won’t show you. You wouldn’t really convert this way, but it helps to see it in the long form. This way you know what your teacher is showing you isn’t some pixie dust magic:
Now that you can do that, you can probably go the other way too:
And how about checking your work? Nevermind the devil box (aka the calculator), the more you check your own work by hand, the more your confidence in your own math abilities will be. Try doing this:
What do you think? Will this help you remember? Do you have another way to remember? Share it in the comments.
One of the common errors in algebra is canceling bits in fractions that can’t be canceled. To remember the rule, though, you don’t have to memorize anything. You only have to think of a plain arithmetic problem to compare it.
To help you remember what’s allowed with problem:
think about this simpler problem:
Like this:
And just to keep you straight, here are the requirements (and a couple of examples) for the fancy <cue music> “distributive property.”
What do you think of this explanation? Post your thoughts in the comments.
