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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.
A single-term expression is a monomial only if all of its variables have whole numbers — non-negative and integers — as exponents. However, variables with positive exponents in the denominator are excluded because they are equivalent to a power in the numerator with the opposite exponent, according to the Quotient of Powers Property. Consider the following example.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.
Izabella feels confused. Help her solve these problems.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.
Once again, they have run into a problem. The polynomials are not simplified yet. Join their study group and give them a hand.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 |