Question

From the sum of 3x² − 5x + 2 and −5x² − 8x + 6, subtract 4x² − 9x + 7.

Answer 1

Adding:
(3x² − 5x + 2) + (−5x² − 8x + 6)
Rearranging and collecting the like terms:
(3-5)x² +(− 5-8)x + 2 +6
= -2x² − 13x + 8
Subtract 4x² − 9x + 7 from -2x² − 13x + 8.

Change the sign of each term of the expression that is to be subtracted and then add.
Term to be subtracted = 4x² − 9x + 7
Changing the sign of each term of the expression gives -4x² + 9x - 7.
On adding:
( -2x² − 13x + 8 )+(-4x² + 9x - 7 ) = -2x² − 13x + 8 -4x² + 9x - 7
= ( -2-4)x² +(−13+9)x + 8 -7
= -6x² − 4x + 1