Question

How much less than x − 2y + 3z is 2x − 4y − z?

Answer 1

To calculate how much less than x − 2y + 3z is 2x − 4y − z, we have to subtract 2x − 4y − z from x − 2y + 3z.

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

 Term to be subtracted = 2x − 4y − z
Changing the sign of each term of the expression gives -2x + 4y + z.
On adding:
(x − 2y + 3z)+(-2x + 4y + z )
= x − 2y + 3z-2x + 4y + z 
= (1-2)x +(−2+4)y + (3+1)z
 = -x + 2y + 4z