What must be subtracted from (x3−3x2+5x−1) to get (2x3+x2−4x+2) ?
−x3−4x2+9x−3
Let the expression to be subtracted be y.
Hence,
(x3−3x2+5x−1)−y=2x3+x2−4x+2
On rearranging the terms,
y=(x3−3x2+5x−1)−(2x3+x2−4x+2)
y=x3−3x2+5x−1−2x3−x2+4x−2
y=x3−2x3−3x2−x2+5x+4x−1−2
⇒y=−x3−4x2+9x−3
So we have to subtarct (−x3−4x2+9x−3) to get the required value.