Question

Find the value of C that completes the square for x^2-2x + C

Answer 1

C = 1.

Explanation:

x^2 - 2x = (x - 1)^2 - 1 so:

x^2 - 2x + C = (x - 1)^2 - 1 + C

So to get a perfect square C must be 1 ( as -1 + 1 = 0):-

(x - 1)^2 - 1 + 1 = (x - 1)^2

Checking this:

x^2 - 2x + 1

= (x - 1)(x - 1) which is a perfect square./