- Books Name
- CBSE Class 7 Mathematics Book

- Publication
- Param Publication

- Course
- CBSE Class 7

- Subject
- Mathmatics

**Like terms : **The terms having the same literal factors are called like or similar terms.

In the algebraic expression 12a^{2 }– 15b^{2} + b^{2} –17a^{2 }+ 8ab + 9, we have, 12a^{2} and –17a^{2} as like terms and also – 15b^{2} and b^{2} are like terms.

**Unlike terms : ** The terms not having same literal factors are called unlike or dissimilar terms.

In the algebraic expression 3p^{2}q + 5pq^{2} – 7pq – 9qp^{2}, 5pq^{2 }and –7pq are unlike terms.

- Books Name
- class 7 Mathematics Book

- Publication
- ReginaTagebücher

- Course
- CBSE Class 7

- Subject
- Mathmatics

**Types of algebraic expressions. Trinomials**

A trinomial algebraic expression is an algebraic expression that has three terms.

The prefix 'tri' in 'trinomial' stands for 3 terms.

To add two trinomials, you must:

1) remove the brackets (without changing the signs, because the “+” sign is in front of the brackets);

2) add the like terms.

*Example:*

**Add trinomials: **

(−5x^{3}+3y−5y^{2})+(8x^{3}+5y^{2}−2y)

*1) Remove the brackets:*

(−5x^{3}+3y−5y^{2})+(8x^{3}+5y^{2}−2y)==−5x^{3}+3y−5y^{2}+8x^{3}+5y^{2}−2y.

*2) Find the like terms and add:*

−5x^{3}¯¯¯¯¯¯¯¯+3y−5y^{2}+8x^{3}¯¯¯¯¯¯¯¯+5y^{2}−2y=3x^{3}+3y¯¯¯¯¯¯−5y^{2}+5y^{2}−2y¯¯¯¯¯¯=3x^{3}+y.

To multiply a trinomial by a trinomial, you need to multiply each term of one trinomial by each terms of another trinomial and add the resulting products.

(a+b+c)⋅ (d+e+f)==a⋅d + a⋅e +a⋅f +b⋅d +b⋅e +b⋅f +c⋅d +c⋅e +c⋅f = ad + ae + af + bd + be + bf + cd + ce + cf

**To subtract two trinomials , you must:**

1) remove the brackets and change the signs of the trinomials that are preceded by the sign "−" to the opposite;

2) combine the like terms of the trinomials.

*Example:*

*Let us calculate the difference of trinomials *(7x^{2}+3x−2)* and *−2x^{2}+2x+3

*1)** Write down the difference of the trinomials and remove the brackets, taking the signs before the brackets into account:*

(7x^{2}+3x−2)−(−2x^{2}+2x+3)=7x^{2}+3x−2+2x^{2}−2x−3

*2) Find the like terms:*

7x^{2}¯¯¯¯¯+3x¯¯¯¯¯¯¯¯−2 +2x^{2}¯¯¯¯¯−2x¯¯¯¯¯¯¯¯−3

*3) Combine the like terms:*

7x^{2}¯¯¯¯¯+3x¯¯¯¯¯¯¯¯¯¯¯¯−2+2x^{2}¯¯¯¯¯¯¯¯−2x¯¯¯¯¯¯¯¯¯¯¯¯−3=(7+2)x^{2}+(3−2)x−2−3=9x^{2}+1x−5

*4) If the coefficient of a term is *1*, then usually we do not write it:*

9x^{2}+1x−5=9x^{2}+x−5

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## Batch List

###### Medha Sharma

Course : CBSE Class 7

Start Date : 09.02.2023

End Date : 18.07.2023

Types of Batch : Classroom