Question

How do you complete the square for `x^2 + 11x`?

Answer 1

`x^2+11x = (x+11/2)^2-11^2/(2^2) = (x+11/2)^2-121/4`

Explanation:

In general,

`ax^2+bx+c = a(x+b/(2a))^2+(c-b^2/(4a))`

Notice the `b/(2a)` term.

In our case `a=1` and `b=11` hence the `11/2`