MA, Stanford University
Teaching in the San Francisco Bay Area
Alissa is currently a teacher in the San Francisco Bay Area and Brightstorm users love her clear, concise explanations of tough concepts
There are different rules to follow when multiplying exponents and when dividing exponents. If we are multiplying similar bases, we simply add the exponents. If we are dividing, we simply subtract the exponents. If an exponent is outside the parentheses, it is distributed to the inside terms. It's important to understand the rules of multiplying exponents so that we can simplify expressions with exponents.
When you get to the chapter on exponents, your teacher is going to be assigning lots and lots of homework of problems. Mostly because they'll probably be short. Well you got to be really careful though because a lot of times when I assign lots of exponents problems, students do most of them incorrectly because they try to rush through. Please be careful when you're doing these exponent problems there's lots of places to make mistakes. One place students make mistakes is they to memorize all of these exponents properties that we'll go over in a second and then they end up getting them confused in their brain. So I am going to go over these but I'm going to ask that you don't memorize them unless you think you're like an A level student. It's okay if you're a good memorizer and you're like a B or C student, you can also try to memorize these. But be really careful a lot of errors happen when students are just going through carelessly and they make silly mistakes because they thought they memorized the properties.
And one more thing before we go over these, these are just the properties of multiplying and dividing with exponents, there are other properties have to do with exponents that are zero and negative exponents, we'll get to those in another video. But for now let's just check this out I'm going to do these both using variables and also using numbers you guys can get a sense of what I mean. x to the n, to the m power is equal to the x to the n multiplied by m. Here's what it means if you're using numbers, 3 squared to the fourth power would be equal to 3 to the eighth power. That's what it would look like in terms of numbers, and we'll get into why that is when we start doing more and more practice problems.
Here's another property, if I have 3 times 2 to the fourth power like xy to the m, it's equal to x to the m times y to the m. So that would be 3 to the fourth times 2 to the fourth, it's almost like that little exponent distributes on the each of these pieces in the base as long as they are in parenthesis. Here is another property are you getting tired of trying to memorize them yet, don't worry with memorizing. You can work on that and I'll show you that when we do problems. x to the n times x to the m is equal to x to the n plus m. What does that mean? It means this, if you have the same base, like 3 to the 1 times 3 to the second power see how all those are the same base but different exponents that can be simplified by adding those guys 1 plus 2.
Again if you're not a good memorizer don't be memorizing these, we're going to go over them and make them make more sense in just a second. Next one x to the n divided by x to the m is equal to the difference of the exponents. So if I had 3 to the fourth power on top of the 3 squared that would be equal to the same thing as 3 to the 4 take away 2 or 3 squared.
Last but not least if you have a fraction raised to an exponent it's kind of like this exponent gets distributed on to both pieces of that base. Like 3 halves to the fourth is the same thing as 3 to the fourth over 2 to the fourth. So I'm just going to say this one last time I know I've already said it like lots of times, if you're not someone whose a good memorizer don't even try to memorize these because you're going to get them jumbled in your head. It's always better to write out every number and get it correct than to do it shortcut method easy in memorizing but you get it wrong.
