Adding and Subtracting Polynomials

A polynomial in one variable x can be written in standard form as a0xn + a1xn-1 +... + an. Here, a0, a1,..., an are real-number coefficients, n is a non-negative, whole number and the powers of x decrease as we move from left to right. 

For example: 4x³ - 2x² + 5x + 7 is a polynomial of degree 3 with 4 terms.
 

Based on the number of terms, there are 3 types of polynomials. 

• Monomial: Polynomials with only one term are monomials. Some examples of monomials are: 7x3, -4a2b, 12y

• Binomial: These are polynomials having two terms. x2−9, 3a + 5b, 4m3 + 2 are all examples of binomials.

• Trinomial: As the name suggests, these polynomials have three terms. For example: x2 + 3x + 2, a3 − a + 7, 2m2 + 5m + 1

Polynomials can have one or more terms; they are classified by the number of terms. The degree of a polynomial refers to the highest value of the exponent it has. For instance, in the polynomial 3x2 + 2x - 5, the highest exponent is 2; therefore, it is also the degree of the polynomial. 
 

There are two rules to be followed when adding polynomials:

1. Like terms should always be grouped together. Like terms refer to terms having the same variables, as well as exponential powers. Terms having different variables, exponents, or both are unlike terms.
2. Signs of terms do not change during addition.
3. Let us understand polynomial addition using the following steps to solve an example:

Question: Add the polynomials (3x2 - 5x + 2) + (4x2 - 2x + 7)

Solution:

Step 1: Arrange the polynomials in standard form
3x2 - 5x + 2 and 4x2 - 2x + 7 are already in standard form.

Step 2: Group like terms
(3x2 + 4x2) + (-5x - 2x) + (2 + 7)

Step 3: Add the coefficients of like terms
3x2 + 4x2 = 7x2
-5x + (-2x) = -7x
2 + 7 = 9
Answer: 7x2 - 7x + 9
This sum was solved by adding polynomials horizontally.

We can also do the addition of polynomials vertically. Let us take an example for the same:

Question: Add the polynomials (4x2 + 3x + 5) + (2x2 + 6x + 1)
Solution: 

Step 1:Arrange polynomials one below the other and make sure all like terms are aligned together.
                4x²   + 3x   + 5  
              + 2x²   + 6x   + 1  

Step 2: Then, calculate the like terms.
To add similar terms, we add the coefficients of the terms and write the variable as is.
4x2 + 2x2. = 6x2
3x + 6x = 9x
5 + 1 = 6
 6x2 + 9x + 6 is the sum of given polynomials.

How to Subtract Polynomials?

The subtraction process of polynomials is similar to the addition process. Addition and subtraction of polynomials can be done two-ways: horizontally and vertically. Two rules to follow when subtracting polynomials are:
Like terms must always be grouped.
The signs of all terms in the second polynomial change because the minus sign is distributed throughout the second polynomial.

Let's take an example to understand the steps of polynomial subtraction:

Question: Subtract (5x2 + 7x + 2) − (3x2 + 4x - 6)
Solution: Let’s solve this question using the horizontal method.

Step 1: Arrange polynomials in their standard form (decreasing order of exponents)  and place them next to each other with a subtraction sign between them.
 Since they are already in standard form and placed horizontally,  
(5x2 + 7x + 2) − (3x2 + 4x - 6)
 We can move to the next step.

Step 2:Distribute the minus sign to all the terms of the second polynomial
(5x2 + 7x + 2) − (3x2 - 4x + 6)  

Step 3: Group like terms,
(5x2 − 3x2) + (7x − 4x) + (2 + 6)

Step 4: Calculate
2x2 + 3x + 8
Subtracting (3x2 + 4x - 6) from (5x2 + 7x + 2) gives us the answer 2x2 + 3x + 8.

Let us solve another example by vertically subtracting the polynomials:
Question: Subtract (6x2 + 5x + 8) − (3x2 + 2x + 4)
Solution:

Step 1: Arrange polynomials in standard form. 
The given polynomials are already in their standard form, i.e., written in descending order of exponents.
(6x2 + 5x + 8) − (3x2 + 2x + 4)

Step 2: Place polynomials vertically, with like terms aligned one above the other.
   6x²   + 5x   + 8  
- (3x²   + 2x   + 4)

Step 3: In case there are any missing variable terms like x2, x etc, we can add a zero coefficient as a placeholder(0x2, 0x). Here, we can skip this step since no power terms are missing.

Step 4: Change the signs for the second polynomial
 6x²   + 5x   + 8  
-3x2    -2x     - 4

Step 5: Calculate
6x2 - 3x2 = 3x2
5x - 2x = 3x
8 - 4 = 4
Therefore, upon subtracting the given terms, we get the answer as: 3x2 + 3x + 4
 

Polynomials are key in solving practical problems across science, engineering, economics, and everyday life. Adding and subtracting polynomials helps predict and model real-world scenarios, including:

• Measurement calculations in construction and architecture
  Architects use polynomial expressions while calculating the area, perimeter, or volume of irregular shapes in building designs.

• Motion and force equations in engineering 
  In kinematics and mechanical systems, position, velocity, and acceleration are modeled using polynomials. Engineers find net forces or combined motions by adding or subtracting these values.

• Representing cost, revenue, and profit functions in business 
  Polynomial functions represent cost, revenue, and profit functions over time or production quantity. Businesses use addition or subtraction of these functions for decision-making in regard to sales and restocking.

• Describing curves and transformations in animation 
  polynomial model curves and transformations for better transitions in computer graphics.

• Population modeling for research and mapping
  Polynomial expressions can be used to model population growth for census, pollution levels, or environmental sciences, or resource consumption trends across regions for informed decisions.