∵A=1+2x 2﹣3x 3,B=3x 3﹣2x 2﹣5x﹣4,
∴2A﹣(A﹣B)
=A+B
=(1+2x 2﹣3x 3)+(3x 3﹣2x 2﹣5x﹣4)
=1+2x 2﹣3x 3+3x 3﹣2x 2﹣5x﹣4
=﹣3﹣5x.
当x=﹣
时,
原式=﹣3﹣5×(﹣
)
=﹣3+
=﹣
.
∵A=1+2x 2﹣3x 3,B=3x 3﹣2x 2﹣5x﹣4,
∴2A﹣(A﹣B)
=A+B
=(1+2x 2﹣3x 3)+(3x 3﹣2x 2﹣5x﹣4)
=1+2x 2﹣3x 3+3x 3﹣2x 2﹣5x﹣4
=﹣3﹣5x.
当x=﹣
时,
原式=﹣3﹣5×(﹣
)
=﹣3+
=﹣
.