That is, according to the formula: (x 土 a)^2 = x^2 土 2ax + a^2

Formulate x^2 - 8x + 25 as (x - a)^2 + b = x^2 - 2ax + a^2 + b:

For this purpose: x^2 - 8x + 25 = x^2 - 2*4*x + 4^2 + 9 = (x - 4)^2 + 9<

That is, x^2 - 8x + 25 = (x - 4)^2 + 9

The general case: x^2 + ax + b = x^2 + 2*(a/2)*x + a^2/4 + b - a^2/4

= (x + a/2)^2 + b - a^2/4 (1)

For this example: a = - 8 b = 25 Substituting into (1) gives:

(x-4)^2 + 25 - (-8)^2/4 = (x-4)^2 + 9

If the coefficient of the x^2 term is not 1, present the common factor and then do the above operation.