Adding Polynomials || How to add different polynomials - WTSkills- Learn Maths, Quantitative Aptitude, Logical Reasoning

In this post we will learn methods of adding different polynomials.

To understand the chapter you should have basic knowledge of polynomials, like terms and BODMAS rules.

Methods of adding Polynomials

Here we will learn two methods.

(a) Horizontal addition of polynomials
(b) Vertical addition of polynomials

Both the method follow below rules:

(1) In polynomials, only like terms are added or subtracted.
Like terms are the entity with the same variables.

(2) While adding like terms, only coefficient is added, the variables remain the same.

For Example
Add the below expression.
$\mathtt{6x^{2} +\ 7x\ +\ 3x^{2} +\ 4}$

Here $\mathtt{6x^{2} \ \&\ \ 3x^{2}}$ are the like terms. Hence, only these two entities can be added.

$\mathtt{\Longrightarrow \left( 6x^{2} \ +\ \ 3x^{2}\right) \ +\ 7x\ +\ 4}\\\ \\ \mathtt{\Longrightarrow \ 9x^{2} +\ 7x\ +\ 4}$

Note that only coefficient of entity is added, the variable part remained the same.

Now let us study different methods of adding the polynomials.

Horizontal addition of polynomials

For adding the given polynomials, follow the below steps:

(a) Identify the like terms in the polynomial

(b) Arrange the like terms under one bracket

(c) Add the coefficients of like terms and keep the variables constant.

Given below are some examples for your understanding.

Examples of Adding Like terms

Example 01
Add the below polynomials.
4x + 6y ; 3x ; 11x + 2y

Writing all the polynomials in addition form
4x + 6y + 3x + 11x + 2y

Now follow the below steps:

(a) Identify the like terms

(b) Arrange the like terms under one bracket

⟹ (4x + 3x + 11x) + (6y + 2y)

⟹ 18x + 8y

Hence adding all the three expressions result in 18x + 8y

Example 02
Add the given three expressions.
$\mathtt{3m^{2} -2mn\ +\ 6n^{2}}\\ \\ \mathtt{-m^{2} +6mn\ +\ n^{2}}\\ \\ \mathtt{8m^{2} +\ 4mn\ -\ n^{2}}$

Solution
Writing all the expression in addition form.

\mathtt{\left( 3m^{2} -2mn\ +\ 6n^{2}\right) \ +\ \left( -m^{2} +6mn\ +\ n^{2}\right) \ }\\ \\ \mathtt{+\ \left( 8m^{2} +\ 4mn\ -\ n^{2}\right)}

Arranging the like terms under one bracket..

\mathtt{\Longrightarrow \left( 3m^{2} -m^{2} \ +\ 8m^{2}\right) +( -2mn\ +6mn\ +\ 4mn)}\\ \\ \mathtt{+\ \left( \ 6n^{2} \ +\ n^{2} -n^{2}\right)}\\\ \\ \mathtt{\Longrightarrow \ 10m^{2} +8mn+6n^{2}}

Example 03
Add the below expressions
$\mathtt{2x^{3} +\ 2x^{2} +\ 4}\\ \\ \mathtt{3x^{2} +\ 6\ +\ 7x^{3}}$

Solution
First write the expression in addition form.

$\mathtt{\Longrightarrow \left( 2x^{3} +\ 2x^{2} +\ 4\right) +\ \left( 3x^{2} +\ 6\ +\ 7x^{3}\right)}$

Arranging the like terms in single bracket.

$\mathtt{\Longrightarrow \ \left( 2x^{3} \ +\ 7x^{3}\right) +\ \left( 2x^{2} +\ 3x^{2}\right) \ +\ ( 4\ +\ 6)}\\\ \\ \mathtt{\Longrightarrow \ 9x^{3} +\ 5x^{2} +\ 10}$

Example 04
Add the below polynomials
7x + 5y + z ;
6x + 3y ;
11x + 9z

Solution
Writing all the expression in addition form.

⟹ (7x + 5y + z) + (6x + 3y) + (11x + 9z)

Arranging the like terms in bracket.

⟹ (7x + 6x + 11x) + (5y + 3y) + (z + 9z)

⟹ 24x + 8y + 10z

Example 05
Add the below polynomials
$\mathtt{-x^{3} +\ 6xy\ +\ x}\\ \\ \mathtt{y\ +\ 10xy}$

Solution
Adding the polynomials

$\mathtt{\Longrightarrow \ \left( -x^{3} +\ 6xy\ +\ x\ \right) \ +\ ( y\ +\ 10xy)}\\\ \\ \mathtt{\Longrightarrow \ -x^{3} +\ 6xy\ +\ 10xy\ +\ x+y}\\\ \\ \mathtt{\Longrightarrow \ -x^{3} +\ 16xy\ +\ x\ +\ y}$

Vertical Addition of Polynomial

Given below are steps for vertically adding the polynomials.

(a) Find the like terms among the given polynomial.

(b) Vertically align the like terms so that they are in same column

Given below are examples for further understanding.

Vertically addition of Polynomials Examples

Example 01
Add the given polynomials
x + 2yz + 3y;
2y + 9yz

Solution

(a) Find the like terms among given polynomial

(b) Vertically align the like terms in same column and add the entities

Hence, x + 11yz + 5y is the solution.

Example 02
Add the given polynomials.
$\mathtt{x^{3} +\ 6xy\ -9x}\\ \\ \mathtt{x^{2} \ +\ 7xy}\\ \\ \mathtt{3x^{3} +\ 2x}$

Solution
Vertically align the like terms and add the entities vertically

Hence, $\mathtt{4x^{3} +\ x^{2} +13xy\ -\ 7x}$ is the solution

Example 03
Add the below polynomials
$\mathtt{m^{2} +\ 5m^{3} +\ n^{2}}\\ \\ \mathtt{6mn\ +\ 7m^{2}}\\ \\ \mathtt{-4m^{2} +\ m^{3}}$

Solution
Vertically align the like terms and do the addition.

Hence, $\mathtt{6m^{3} +4m^{2} +\ n^{2} \ +6mn}$ is the solution.

Frequently Asked Question – Polynomial addition

(01) Can you combine the below expression
x + 4y and xy + yz

No!!
All the entities contain different variables.

x ⟹ variable x
4y ⟹ variable y
xy ⟹ variable xy
yz ⟹ variable yz

Addition is only possible between entities of same variables.

(02) What are like terms? Can you share some examples.

Entities with same variables are known as like terms.

Consider the equation
$\mathtt{x^{2} y\ +\ 3y^{3} +\ 5x^{2} y}$

Here the first and third entities are like variables.

(03) Can we add entities with different power?

No!! We cannot add entities with different exponents.

For example, $\mathtt{x^{2} \ \&\ x^{3}}$ are entities with different power and cannot be added.