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.

Here we will learn two methods.

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
\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.

(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
4x + 6y ; 3x ; 11x + 2y

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

(a) Identify the like terms

(b) Arrange the like terms under one bracket

⟹ (4x + 3x + 11x) + (6y + 2y)

(c) Add the coefficients and keep the variables intact

⟹ 18x + 8y

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

Example 02
\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
\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
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
\mathtt{-x^{3} +\ 6xy\ +\ x}\\ \\ \mathtt{y\ +\ 10xy}

Solution

\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}

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

(c) Add the coefficient of like terms and leave the variables as it is.

Given below are examples for further understanding.

#### Vertically addition of Polynomials Examples

Example 01
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
\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
\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.

(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.