# Subtraction of Algebraic Expression

In Subtraction of Algebraic Expression from another,follow the following steps

1) Change the signs.

‘+’ ---> ‘- ‘

‘-‘ ----->’+’
of all the expressions which is to be subtracted and then the two expressions are added.
_______________________________________________________________________

Example :

1) Subtract -7x from 5x

Solution :

= 5x – ( -7x)
=5x + 7x
= 12x
_______________________________________________________________________
2)x2 + y2 + 3xy from 4x2 + 2xy – 3y2

Solution :

=(4x2 + 2xy – 3y2) – (x2 + y2 + 3xy)
= 4x2 + 2xy – 3y2 - x2 - y2 - 3xy
=4x2 + 2xy – 3y2 - x2 – y2 - 3xy
= 3x2 - xy – 4y2
_______________________________________________________________________
3)What should be subtracted from a3 - 4a2 + 5a – 6 to obtain
a2 - 2a + 1 ?

Solution:

Let 'X' denote the required expression,
(a3 - 4a2 + 5a – 6) – X = a2 - 2a + 1
Hence , X = (a3 - 4a2 + 5a – 6) – (a2 - 2a + 1)
= a3 - 4a2 + 5a – 6 - a2 + 2a – 1
= a3 - 4a2 +5a – 6 - a2 +2a –1
= a3 - 5a2 + 7a – 7
_________________________________________________________________
4)Subtract a3 - 4a2 + 5a – 6 from the sum of 3a3 + a2 + 1 and a2 -2?

Solution:

= [(3a3 + a2 + 1) + a2 -2)] - (a3 - 4a2 + 5a – 6 )
= (3a3 + a2 + 1+ a2 -2) - (a3 - 4a2 + 5a – 6 )
= (3a3 + 2a2 -1) - (a3 - 4a2 + 5a – 6 )
= 3a3 + 2a2 -1 - a3 + 4a2 - 5a + 6
= 3a3 + 2a2 -1 - a3 + 4a2 - 5a + 6
= 2a3 + 6a2 - 5a + 5
Algebraic Expressions

Like and Unlike terms in Algebra