Question

Subtract:

a − 2b − 3c from −2a + 5b − 4c

Answer 1

Change the sign of the term of the expression that is to be subtracted and then add.

Term to be subtracted = a − 2b − 3c
 Changing the sign of each term of the expression gives -a +2b + 3c.
On adding:
(−2a + 5b − 4c)+(-a +2b + 3c ) = −2a + 5b − 4c-a +2b + 3c
= (−2-1)a + (5+2)b +(−4+3)c
= −3a + 7b − c