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## Algebra 2

### Course: Algebra 2 > Unit 1

Lesson 4: Multiplying monomials by polynomials- Multiplying monomials
- Multiply monomials
- Multiplying monomials by polynomials: area model
- Area model for multiplying polynomials with negative terms
- Multiply monomials by polynomials: area model
- Multiplying monomials by polynomials
- Multiply monomials by polynomials
- Multiplying monomials by polynomials review

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# Multiplying monomials by polynomials: area model

CCSS.Math: ,

Sal expresses the area of a rectangle whose height is 4 and width is x²+3x+2.

## Want to join the conversation?

- Is polynomials the same thing as trinomials?(6 votes)
- Trinomials are just one type of polynomial. Specifically they are a polynomial with 3 terms.

There are also monomials (1 term) and binomials (2 terms) and other polynomials that have more than 3 terms.(25 votes)

- Why are all of the videos have easy math problems? But when I do the math it's a complicated problem?(11 votes)
- this is sooooo confusing for me(4 votes)
- Why are all of the videos have easy math problems? But when I do the math it's a complicated problems(2 votes)
- As long as you apply the concept/idea of the video lectures to the exercise, it's the same as any problems. The point is to understand the concept.(2 votes)

- What is a trinomial?

How can it relate to real-world situations?(1 vote)- A trinomial is a polynomial with three terms. Polynomials are the larger category under which you can find monomials, binomials, and trinomials.(2 votes)

- If you had an equation:

7x^2 times 3x^2 would the answer be 21x^4 or 21x^2.

Would you add the exponents together or not because they are not the same.(1 vote)- If you multiply same bases, you add the exponents, so the first answer (21x^4) is correct. If you add 7x^2 + 3x^2 = 10 x^2. When you say "they are not the same," that is not correct, the coefficients are different, but the bases ("x") are the same.(2 votes)

- like I get it but I don’t get it at the same time haha(1 vote)
- Do I add the variables after solving the equation.

Ex. 24a^4+36a^3+12a^2

Do i add the variables??(1 vote)- Your polynomial is a simplified as it can be. You can only add like terms. None of the varialbes match and have matching exponents.

Hope this helps.(0 votes)

- how do you do this i dont understand(0 votes)
- Okay so we are going to imagine a rectangle... The rectangle is going to be split in three sections at the top with three different numbers... Okay so the first side will be a^2 the next number will be 5a and the final multiplying number will just be 4...

So we should have a^2+5a+4...

Now on the side of the rectangle we are going to divide by the number 7...

So we go straight for the first multiplication step...

7*a^2

So we see there is no number for us to multiply so the answer to this problem... or this part of the problem would be 7a^2+

Next is 7*5a...

here is our first multiplication problem 7*5a is 35

So we take the 35 and the answer to this step looks like this 35a

Problem so far...7a^2+35a+

You would notice that there is no exponent and that is because there is only one a... Now lets say we had 4 a's then we would use exponents to make it look like this...

35a^4... But there is no need for that kind of math right now...

now its just 7*4 with no a and that answer is 28...

So our answer would be 7a^2+35a+28...

BOOM!! You just simplified the whole rectangle!

Now was that not easy?

I hope this helps...

-Frenchy Starfire(1 vote)

- s polynomials the same thing as trinomials?(0 votes)
- Trinomials are a type of polynomial, specifically a polynomial with three terms. In general, a polynomial can have any number of terms.(2 votes)

## Video transcript

- [Voiceover] We're asked
to express the area of the entire rectangle below as a trinomial. We have our rectangle here
and it's broken up into these three smaller rectangles. And we see for all of these rectangles, the height here is four
units and then the widths are expressed in terms,
or at least the first two, are expressed in terms of
x and then this last one has a width of two. So what's the area of
the entire rectangle? I encourage you to pause the
video and think about it. What's the area of this blue, this blue, it looks like a square,
but let's just call it a rectangle, which all
squares are rectangles so that's safe. Well, it's going to be the
height times the width. So the area here is
going to be the height, which is four, times the width, which is x squared. And then to that, we want
to add the area of this, I guess we could say this
salmon colored rectangle and well that's going
to be the height four times the width 3x. So we could say four times 3x, we could write it like that, but what is 4 times 3x? Well, that's going to be 12x. You have 3x four times, I have 12 xs, so that's going to be 12x. 12x is the area of this
salmon colored rectangle. And then, finally, the area
of this green rectangle, we actually can figure out
it exactly, we don't even have to express it in terms of a variable. Its height is four, its width is two, so the area's going to be
four times two, or eight. And we are done.