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### Course: Algebra (all content)>Unit 10

Lesson 4: Multiplying monomials

# Multiplying monomials to find area: two variables

Sal expresses the area of a rectangle with length 4xy and width 2y as a monomial. Created by Sal Khan and Monterey Institute for Technology and Education.

## Want to join the conversation?

• can a coefficient number be negative
• I can see at that you have put a video of multiplying monomials, but I wanted a video of dividing monomials. Is there such a video somewhere on this website?
• same here specifically dividing monomials by binomials
(1 vote)
• Is there a video explaining what polynomials, monomials, and binomials are?
(1 vote)
• Can't the area also be founds by adding 4xy+4xy+2y+2y, which = 8xy+4y? Can someone show me how this is = to 8xy^2? Thanks
(1 vote)
• Area = Length * Width
You are finding the perimeter = 2(length) + 2(width).
They are not the same.
• Is there a video that helps with binomials,monomials,polynomials?
(1 vote)
• How do u multiply and divide -48y3 and -8y?
• If you mean -48y cubed, you should type it like this: -48y^3. And multiplying it is simple, -8y is just like saying -8y^1. So really, you are just adding the exponents, 1 and 3 to get four. And 48 times 8 is equal to 384. So when you multiply it, the answer is 384y^4. To divide, you just subtract 1 from 3, and divide 48 by 8 to get 6y^2. Hope this helped.
• What exactly is the term that is both behind 4 and 2?
• They are not terms but factors (something you multiply with).
You use letters instead of numbers to indicate that it is a variable. The value of x and y could be any number (in this case they should be positive since sidelengths are positive)
• How do I get rid of negative exponenants in dividing monomials
(1 vote)
• Negative exponents, remember, mean 1/whatever the rest is. You can "flip" the expression to the other part of the fraction and make it a positive exponent.
(1 vote)
• How do u divide the monomials if it has negative exponents
(1 vote)
• When you have negative exponents, it is the same thing as its reciprocal(or as I like to call it, flipping it). When you divide your exponents, you subtract (to be specific, you subtract the divisor's [bottom one] exponent from the dividend's [top one] exponent. Just say if you don't understand, okay?
(1 vote)
• He put the width where the length should be, and he placed the length where the width should be in the beginning.
(1 vote)
• Yeah, that's true, but it doesn't matter where he puts it, he still gets the same answer,