While adding or subtracting,

We add subtract like terms

 

Add 3 𝑥 & 4𝑥

 3𝑥 + 4𝑥

= 𝑥 (3 + 4)

= x × 7

= 7𝑥 

 

Add 8xy & 2𝑥

8𝑥y + 2𝑥  

Since 8𝑥y & 2𝑥 are unlike terms

We cannot add them

 

Add 8𝑥y, 4𝑥y & 2𝑥y

8𝑥y + 4𝑥y + 2xy

= xy (8 + 4 + 2)

= xy (14)

= 14𝑥y     

 

Subtract 4n from 7n

7n − 4n

= n(7 − 4)

= n × 3

= 3n

 

Subtract 5ab from 11ab

11ab − 5ab

= ab (11 − 5)

= ab × 6

= 6ab

 

Now,

Suppose our expressions are bigger

 

Add 3x + 11 & 7x − 5

(3𝑥 + 11) + (7𝑥 – 5)

We group like terms together

= (3x + 7x) + (11 − 5)

 = 10𝑥 + 6

 

Add (3x + 11 + 8z) & 7x − 5

(3𝑥 + 11 + 8z) + (7x − 5)

= (3x + 7x) + (11 − 5 ) + 8z

= x (3 + 7) + (6) + 8z

= 10x + 6 + 8z

= 10x + 8z + 6   

 

  Subtract (a − b) from 3a − b + 4

(3a − b + 4) − (a − b)

= 3a − b + 4 − a + b

= (3a − a) + (−b + b) + 4

= (3a − a ) + (b − b) + 4

= 2a  + 0 + 4

= 2a + 4

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Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 13 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.