Question

What should be added to 2x³ + 6x² – 5x + 8 to get 3x³ – 2x² + 6x + 15?

Answer 1

3x³ – 2x² + 6x + 15 – (2x³ + 6x² – 5x + 8)

= 3x³ – 2x² + 6x + 15 – 2x³ – 6x² + 5x – 8

= 3x³ – 2x³ – 2x² – 6x² + 6x + 5x + 15 – 8

= x³ – 8x² + 11x + 7

x³ – 8x² + 11x + 7 must be added to get 3x³ – 2x² + 6x + 15.