Question

what should be added to x2+2x to obtain x2+9​

Answer 1

Answer:

9 - 2x.

Step-by-step explanation:

Let y = x^2 + 9 - (x^2 + 2x)

y = 9 - 2x.

Checking this result:

x^2 + 2x + 9 - 2x

= x^2 + 9.