Math
posted by
Marilyn on
.
Factor the following completely
x^4 – 625

Math 
Damon,
call y = x^2 so x = +/ sqrt y
then
y^2 = 625
y = 25 or y = 25
x = sqrt 25 = +5 or 5
y = sqrt25 = +5i or 5i

Math 
tchrwill,
Any expression of the form a^2  b^2 can be written as (a + b)(a  b).
Therefore, x^4  625) = (x^2 + 25)(x^2  25).
Then, (x^2 + 25)(x + 5)(x  5)