math

Note that (w-13) (w-13) = (w-13)^2

So we have (w-13)^2 = 16

Taking the square root of both sides, we have

(w-13) = 4

Add 13 to both sides .......so, w = 17

Remeber that: (a-b) ² = a ²-2ab+b ²
So you have:
(w-13)(w-13)=16 =>
(w-13) ²=16 =>
w ²-2w*13+13 ²=16 =>
w ²-26w+153=0 =>

Check, Quadratic equation: http://en.wikipedia.org/wiki/Quadratic_equation

femmy:

(w-13)(w-13)=16

FIRST:
Equal your equation to ZERO and do the equation of the (), w ² - 26w + 169 = 16 /////// w ² - 26w + 153 = 0

SECOND:
Use the formula

(-b +/- sqrt(b ² - 4ac))/2a

You'll have w ₁ and w ₂

CPhill:

Note that (w-13) (w-13) = (w-13)^2

So we have (w-13)^2 = 16

Taking the square root of both sides, we have

(w-13) = 4

Add 13 to both sides .......so, w = 17

I would have used CPhill's method
He just made a careless error

w-13=4 OR w-13=-4