Sign In
| 11 Theory slides |
| 13 Exercises - Grade E - A |
| Each lesson is meant to take 1-2 classroom sessions |
Here are a few recommended readings before getting started with this lesson.
LHS * C=RHS* C
Distribute C
Polynomial | Degree | Leading Coefficient |
---|---|---|
P(x)= a_nx^n + a_(n-1)x^(n-1) + ⋯ + a_1x + a_0 | n | a_n |
C* P(x) = C* a_nx^n + C* a_(n-1)x^(n-1) + ⋯ + C* a_1x + C* a_0 | n | C* a_n |
A = l * w From the chat and the diagram made by Kevin, the poster has to be 2 feet shorter and narrower than the wall. Since the wall is 10 feet tall, the poster will be 8 feet tall. The wall is x feet wide, so the width of the poster is x-2 feet.
A polynomial modeling the area of the poster is obtained by substituting the poster's dimensions into the formula for the area. A(x) = (x-2) * 8 ⇓ A(x) = 8x-16 Note that this polynomial gives the area of the poster depending on the width of the wall.
A(x) = 8x - 16 ⇕ A(x) = 8x^1 - 16 The greatest exponent is 1, which means that the degree of the polynomial is 1. The coefficient in front of the term with the greatest exponent is 8. Thus, the leading coefficient is 8.
x= 16
Multiply
Subtract terms
Different methods can be used to multiply two polynomials. The following three methods are based on the Distributive Property.
Distribute x^3 + 2x^2 - 3
Multiply
Commutative Property of Addition
Associative Property of Addition
Add terms
Start by drawing a table that has as many rows as there are terms in the first polynomial and that has as many columns as there are terms in the second polynomial.
Polynomial | Number of Terms |
---|---|
P(x) = x^3 + 2x^2 - 3 | 3 |
Q(x) = x^2 + 4 | 2 |
For example, a table with 3 rows and 2 columns is needed to multiply P(x) by Q(x).
Now, write each term of the first polynomial at the left of each cell of the first column. Similarly, write each term of the second polynomial above each cell of the first row.
Start by multiplying the first terms of each binomial. In this case, multiply x by 3x. ( x+6)( 3x-2) = x( 3x) The empty box is there as a reminder that there are still missing terms.
Next, multiply the outer terms — that is, multiply the first term of the left-hand side binomial by the second term of the right-hand side binomial. In this case, multiply x by -2. ( x+6)(3x - 2) = x(3x) + x( -2)
Now multiply the inner terms — that is, multiply the second term of the left-hand side binomial by the first term of the right-hand side binomial. In this case, multiply 6 by 3x. (x+ 6)( 3x-2) = x(3x) + x(-2) + 6( 3x)
Next, multiply the last terms of each binomial — that is, multiply the second term of the left-hand side binomial by the second term of the right-hand side binomial. In this case, multiply 6 by -2. (x+ 6)(3x - 2) = x(3x) + x(-2) + 6(3x) + 6( -2)
Commutative Property of Multiplication
a* a=a^2
a(- b)=- a * b
Multiply
Add terms
Diego's parents recently bought a piece of land where they plan to raise pigs. They need to fence off a rectangular pigpen before buying the pigs. A farmer friend told Diego that the dimensions of the pigpen, in yards, vary according to the number of pigs x that are being raised in it.
x= 15
Calculate power and product
Multiply
Add terms
A = 1/2* JK* KL The length of the legs can be written using the given expressions. JK &= x+10 KL &= x^3 + 3x^2 - 18x + 54 Next, substitute the previous expressions into the formula for the area. A(x)=1/2( x+10)( x^3 + 3x^2 - 18x + 54) For simplicity, the product of the two polynomials will be computed first. Then, the resulting polynomial will be multiplied by 12. To perform the polynomial multiplication, the Box Method can be used. To do so, start by drawing a 2* 4 table and writing the row and column labels.
JK* KL= x^4+13x^3+12x^2-126x+540
Distribute 1/2
x= 3
Calculate power and product
Add fractions
Add and subtract terms
Calculate quotient
Add terms
x= -4
Calculate power and product
Calculate quotient
Add and subtract terms
x= -1
Calculate power and product
Add fractions
Subtract terms
Calculate quotient
Add and subtract terms
Izabella bought her nephew a bag of magic grow toys for his birthday. Among the toys, there was a trailer and its rectangular container. Initially, the container was 5 centimeters long, 2 centimeters wide, and 3 centimeters high.
The bag says that when the container is placed underwater, its dimensions will increase according to the following functions. The maximum possible size of the container is reached after being underwater for 9 hours. l(t) &= 14t^2 + 5 [0.2cm] w(t) &= - 19t^2 + 2t + 2 [0.2cm] h(t) &= t + 3 Here, t represents the number of hours the toy has been underwater.
V = w * l * h Therefore, to find a polynomial representing the container's volume after passing t hours underwater, multiply the expressions that model the dimensions of the container. w(t) * l(t) * h(t) ⇓ (1/4t^2 + 5) (-1/9t^2 + 2t + 2) (t + 3) By applying the Commutative Property of Multiplication, the previous product can be rewritten to have the two binomials next to each other. (-1/9t^2 + 2t + 2) (1/4t^2 + 5) (t + 3) Then, these two binomials can be multiplied using the FOIL method. For simplicity, the trinomial will not be written during this multiplication.
Distribute - 19t^2 + 2t + 2
Distribute 14t^3, 34t^2, 5t, & 15
Commutative Property of Multiplication
a^m*a^n=a^(m+n)
Multiply fractions
Simplify quotient and product
Commutative Property of Addition
Add and subtract terms
t= 6
Calculate power
a/c* b = a* b/c
Multiply
Calculate quotient
Add and subtract terms
In all the examples seen throughout this lesson, the product of two or more polynomials has resulted in a new polynomial. This is not a coincidence. In fact, the following property guarantees that multiplying polynomials always produces a polynomial.
Given two polynomials P(x) and Q(x), the product P(x)* Q(x) is always a polynomial.
Multiplying two polynomials produces a new polynomial.
In other words, the polynomials are closed under multiplication.
Given two polynomials P(x) and Q(x), compute their product and find the required information.
Multiply ( x+ 2) by ( x -1)
a^m*a^n=a^(m+n)
a(- b)=- a * b
a * 1=a
Add terms
Distribute 4
Substitute expressions
a^m*a^n=a^(m+n)
Multiply
Commutative Property of Addition
Add and subtract terms
Tadeo invited his friends to watch the Champions League final next Sunday. He plans to meet in the backyard and wants to project the game on a wall of the house using a video beam. However, on Saturday night, Tadeo made a test and the image did not look so clear, so he decided to buy a projector screen.
Because the projector screen has a rectangular shape, its area equals its length multiplied by its width. A = l * w From the diagram, we can see that the projector screen is 1.25 feet shorter and narrower from each side of the wall. The wall is 12 feet tall, so we can find the height of the screen by subtracting 1.25 feet from each side. 12-1.25-1.25=9.5 We can find the width of the screen in a similar way. x-1.25-1.25=x-2.5 Let's look at these dimensions in the diagram!
A polynomial modeling the area of the projector screen is obtained by substituting its dimensions into the formula for the area. P(x) = (x-2.5)(9.5) ⇕ P(x) = 9.5x-23.75 Note that this polynomial gives the area of the projector screen depending on the width of the wall. The polynomial can also be written using fractions instead of decimal numbers. To do this, we expand the corresponding terms.
Use any multiplication method to find the following products. Write each result in standard form.
Let's find the required product using the Distributive Property. To start, we distribute the left-hand side binomial to each term of the right-hand side binomial. ( x-4)( x+2) ⇓ ( x-4) x+( x-4) 2 Next, we apply the Distributive Property once more to clear the parentheses and continue combining like terms to simplify the resulting expression.
To find the second product, we will use the FOIL Method. Remember, the word FOIL stands for First, Outer, Inner, and Last.
With this in mind, we can proceed with the required multiplication. Let's start by multiplying the first terms. ( y-3)( y+3) ⇓ y* y The empty box is there as a reminder that there are still missing terms. Next, we multiply the outer terms. ( y-3)(y+ 3) ⇓ y* y + y* 3 Now, it is the turn of the inner terms. (y- 3)( y+3) ⇓ y* y + y* 3 - 3* y Then, we multiply the last terms. (y- 3)(y+ 3) ⇓ y* y + y* 3 - 3* y - 3* 3 Finally, we perform each of the products and combine like terms to simplify the resulting polynomial.
For the third product, let's use the Box Method. First, we determine the dimensions of the table. To do this, let's count the number of terms in each polynomial. ccc Polynomial & & Number of Terms [0.1cm] (z+2) & & 2 [0.1cm] (1-z) & & 2 Since each polynomial has two terms, we will need a table with two rows and two columns. However, we will add an extra row and column to write the terms of each polynomial. Let's write the terms of the first polynomial in the first column and the terms of the second polynomial in the first row.
* | 1 | - z |
---|---|---|
z | ||
2 |
Next, we fill in the table's cells by multiplying the terms written on the corresponding borders of the table.
* | 1 | - z |
---|---|---|
z | z(1) | z(- z) |
2 | 2(1) | 2(- z) |
Finally, let's add all the expressions inside the table and combine like terms.
Write a polynomial, in standard form, that represents the area of the following shaded regions.
To start, let's write the formula for finding the area of a rectangle. A = l * w In our case, the rectangle has dimensions 3x+1 and x-4. Let's substitute them into the formula. A(x) = (3x+1)(x-4) Finally, we write the previous polynomial in standard form by multiplying the two binomials.
The last polynomial represents the area of the given rectangle.
We are interested in finding the area of the given triangle. Therefore, let's begin by writing the formula that we will use.
A = 1/2bh
Since the given triangle is a right triangle, we can use the legs to find the area — that is, b=4g+1 and h=9g-2. Let's substitute these expressions into the formula.
A(g) = 1/2(4g+1)(9g-2)
To write the polynomial A(g) in standard form, we can multiply the two binomials using the FOIL Method.
Note that the area of the shaded region is the area of the rectangle minus the area of the square. A_(Shaded) = A_R - A_S Let's start by finding the area of the rectangle. To do this, we multiply its dimensions.
Next, let's find the area of the square.
Finally, let's subtract the square's area from the rectangle's area.
The obtained polynomial represents the area of the given shaded region.
The surface area of a three-dimensional solid is the sum of the areas of all its faces. Knowing this, write a polynomial representing the surface area of the following solids.
Let's recall the formula for the surface area of a cube. SA =6l ^2 Here l is the side length of the cube. In our case l= 2k+1. Let's substitute this expression into the formula. A(k)=6( 2k+1)^2 Now, let's simplify the obtained expression and write it in standard form.
We can multiply the binomials using the FOIL Method. Recall that the word FOIL stands for First, Outer, Inner, and Last.
Finally, we combine like terms to simplify the polynomial.
The surface area of the given cube is represented by A(k)=24k^2 + 24k + 6.
Let's disassemble the given rectangular prism to see the faces individually.
With this in mind, we can write an expression representing the surface area of the prism. SA = 2A_1 + 2A_2 + 2A_3 ⇓ SA = 2(A_1 + A_2 + A_3) Let's start by finding the area of the bases, whose dimensions are 2p and 3p+1.
In a similar way, let's find the area of the lateral face with dimensions 3p+1 and 9p-5.
Next, let's find the area of the lateral face with dimensions 2p and 9p-5.
Now we are ready to find the polynomial representing the surface area of the rectangular prism. To do this, we substitute the expressions we found for A_1, A_2, and A_3.
Last class, Paulina learned how to use the box method to multiply polynomials. However, while trying to take notes, her teacher erased the board and she could not finish writing all the calculations. Paulina missed two expressions inside the table and the final result!
According to the box method, the top row labels are the terms of one of the polynomials being multiplied. Similarly, the elements at the left of the table form the other polynomial. Let's start by writing the polynomials being multiplied. P(x) &= x^2-2x+6 Q(x) &= 2x^2+3 Now, the cells of the table are filled by multiplying the terms written on the corresponding borders of the table. For example, the top-left cell corresponds to the product of 2x^2 and x^2.
In a similar fashion, the second cell of the second row corresponds to the product of 3 and -2x.
Knowing this, we can find A and B. A &= 2x^2* x^2 = 2x^4 B &= 3(-2x) = -6x Finally, we add the two previous expressions. A+B = 2x^4 - 6x
Now that we know the expressions for A and B, let's begin by writing the in the table.
The result of the polynomial multiplication is the sum of all the expressions inside the table. Therefore, let's add them and combine like terms, if any.
Let R(x) be the product of the following pair of polynomials. That is, R(x)=P(x)Q(x). P(x) &= 2x^3-5 Q(x) &= 4x^6+2
The degree of a polynomial is the highest exponent in the polynomial. Therefore, let's start by finding R(x).
From the resulting polynomial, we can see that the highest exponent is 9. Therefore, the degree of R(x) is 9.
The leading coefficient of a polynomial is the coefficient in front of the term with the highest exponent. Knowing this, let's highlight the leading coefficients of P(x), Q(x), and R(x).
P(x) &= 2x^3-5
Q(x) &= 4x^6+2
R(x) &= 8x^9 - 20x^6 + 4x^3 - 10
The leading coefficients of P(x), Q(x), and R(x) are 2, 4, and 8, respectively. Let's find the required sum using this information!
2 + 4 + 8 = 14
The constant term of a polynomial is the term with no variables including its sign.
R(x) = 8x^9 - 20x^6 + 4x^3 - 10
Therefore, the constant term of R(x) is -10.