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| 12 Theory slides |
| 9 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.
Take a look at the following single-term algebraic expressions. Can a shared characteristic be recognized which would allow for them to be classified reasonably? Drag the expressions and use the colored areas to visualize any common themes, and identify which expressions could be grouped together.
A monomial is an algebraic expression consisting of only one term. It is a product of powers of variables and a constant called the coefficient.
Expression | Why It Is a Monomial |
---|---|
5 | Any constant is a valid monomial. By the Zero Exponent Property, 5x0=5. |
0 | The coefficient of a monomial can be 0. |
-2x5 | The coefficient can be negative. |
5x3y | A monomial can have numbers in the denominator. |
Although they appear to be monomials at first glance, the single-term expressions in the following table do not satisfy the definition of a monomial.
Expression | Why It Is Not a Monomial |
---|---|
2x-1 | The variables of a monomial cannot have negative integer exponents. |
4yx3 | Monomials cannot have variables in the denominator. |
5x3y21 | The variables of a monomial must only have whole number exponents. |
The degree of a monomial is the sum of the exponents of its variable factors. If a variable has no exponent written in it, it is assumed to be 1. Additionally, all nonzero constants have a degree of 0. The constant 0 does not have a degree.
Monomial | Degree |
---|---|
3x | 1 |
x2 | 2 |
9x3 | 3 |
x3y | 4 |
7 | 0 |
13a3b4c5 | 12 |
0 | undefined |
The next applet shows different algebraic expressions. Use the new knowledge introduced previously to determine whether or not these expressions are monomials.
One way that polynomials can be classified is according to the number of terms they have. The following table shows the names used for this classification.
Name | Definition | Example |
---|---|---|
Monomial | A polynomial with a single term. | 3x2y3 |
Binomial | A polynomial with a exactly two terms. | 5xy+3x2y3 |
Trinomial | A polynomial with exactly three terms. | x3−9x+4 |
polynomialis commonly used.
Polynomial | Degree |
---|---|
-5x2y+x2y4−11x2−3 | 6 |
x−11x4+8x3 | 4 |
7 | 0 |
0 | Undefined |
In a polynomial, the coefficient in front of the term with the highest degree is called the leading coefficient.
The following applet alternates between different algebraic expressions. Determine whether or not these expressions are polynomials.
The following applet alternates between different polynomials. Determine the given polynomial's degree or leading coefficient as indicated.
Izabella is improving her understanding of polynomials in her algebra course. However, she has come across some problems where she needs to identify the number of terms of some algebraic expressions and only some of the expressions are polynomials.
For an algebraic expression to be a polynomial, each term must be a valid monomial. A monomial is a single-term expression that is a product of numbers and variables raised to exponents that are whole numbers. Three of the given expressions do not satisfy this definition. That takes them out of the running as being polynomials.
Expression | Reason |
---|---|
4x+x21 | It has a non-integer exponent. |
2x2+5+y-2 | It has a negative exponent. |
2y3x+x2−5y3+9 | It has a variable in the denominator. |
Now that Izabella knows which expressions are polynomials and which are not, she can figure out how to identify their number of terms. Recall that, in any algebraic expression, terms are separated by a plus or a minus sign.
Polynomial | Number of terms |
---|---|
4x−3x3 | 2 |
2x2+5−7y | 3 |
8xy+3x3−3y3+2x | 4 |
Expression | Number of terms |
4x+x21 | 2 |
2x2+5+y-2 | 3 |
2y3x+x2−5y3+9 | 4 |
A polynomial in one variable is expressed in standard form when the monomials that form it are arranged in decreasing degree order. This form can be represented with the following general expression.
anxn+an−1xn−1+⋯+a1x1+a0x0
Izabella, so excited about solving polynomial related problems, has started a study group with Magdalena to work together on another set of polynomials. This time, the polynomials need to be written in standard form and have their characteristics identified.
Classification: Binomial
Degree: 3
Classification: Trinomial
Degree: 5
Factor out x2 & x3
Add and subtract terms
Term | Degree | Coefficient |
---|---|---|
7x2 | 2 | 7 |
x3⇔(1)x3 | 3 | 1 |
Standard Form | ||
---|---|---|
x3+7x2 | ||
Classification | Degree | Leading Coefficient |
Binomial | 3 | 1 |
Commutative Property of Addition
Factor out x & x3
Add and subtract terms
Term | Degree | Coefficient |
---|---|---|
15x⇔15x1 | 1 | 15 |
-8x3 | 3 | -8 |
-2x5 | 5 | -2 |
Standard Form | ||
---|---|---|
-2x5−8x3+15x | ||
Classification | Degree | Leading Coefficient |
Trinomial | 5 | -2 |
Polynomial Equation | Degree |
---|---|
2x3+8x2+2x−12=0 | 3 |
Solutions | |
x=-3,x=-2,x=1 |
Complete the statement with always, sometimes, or never.
Each term of a polynomial is a monomial. |
The difference of two trinomials is a trinomial. |
The sum of two polynomials is a polynomial. |
A polynomial is a monomial or a sum or difference of monomials. In algebraic expressions such as polynomials, we use plus and minus signs to separate individual terms. Therefore, we can conclude that each term of a polynomial is always a monomial.
Every term of a polynomial is always a monomial.
A trinomial is a polynomial containing 3 different monomial terms. Since only like terms can be combined, the difference of two trinomials can have different outcomes. Let's show one where the difference becomes a binomial.
(x^3+4+x) - (x^2+x+4)
⇓
x^3-x^2
However, another set of trinomials could give a difference that is a trinomial.
(x^3+4+x) - (x^2+x-4)
⇓
x^3 - x^2 + 8
Consequently, the difference of two trinomials is sometimes a trinomial.
The difference of two trinomials is sometimes a trinomial.
As we discussed, a polynomial is either a monomial or a sum or difference of monomials. When we add two polynomials, we combine like terms. The sum or difference of like terms will result in new monomials, which means the sum of two polynomials must always be another polynomial.
The sum of two polynomials is always a polynomial.
Notice that we can sometimes obtain 0 as a result of adding polynomials. However, like any constant value, 0 is considered a constant polynomial. In fact, it is called the zero polynomial.
In order to investigate the possible values for a and n, we will rewrite the expression as a product of two powers.
We can continue rewriting a raised to the power of 12 as the square root of a.
Now we can determine which values are possible for a and n.
The coefficient of a monomial must be a real number. Therefore, we cannot substitute negative values for a because doing so would result in a negative argument for the square root, which is undefined. sqrt(a), a≥ 0 Notice that if a=0 we get the zero polynomial. This is also a monomial, which means a=0 is a valid coefficient. Therefore, if we want the given expression to be a monomial, B must be true. B. amust be greater than or equal to zero.
The exponent of a monomial must be non-negative. Therefore, n cannot be negative. We can, however, have n=0, as we then get x^0, which equals 1. This is also a monomial. Therefore, D must be true. D. nmust be greater than or equal to zero. However, since the exponent must also be a whole number, n has to be an even number. Recall that within the exponent we are dividing n by 2. If n were an odd number, we would get a decimal number, which implies that we would not get a monomial. E. nmust be even. Consequently, in order for (ax^n)^(12) to be a monomial, B, D, and E must be true.