Answer :
Step-by-step explanation:
what must be added to 3x - 7 to get x² + 4x - 1 ?
well, what must be added to e.g. 7 to get 11 ?
11 - 7 = 4 must be added.
and in the same way we have to look at more complex expressions too.
(x² + 4x - 1) - (3x - 7) = x² + 4x - 1 - 3x + 7 = x² + x + 6
so, we need to add
x² + x + 6
