Which of the following is x⁴ + y⁴ identically equal to?
(a) (x² + y²)(x + y)(x - y)
(b) (x² + xy + y²)(x² - xy + y²)
(c) (x² + √2xy + y²)(x² - √2xy + y²)
(d) (x² + √3xy + y²)(x² - √3xy + y²)
(e) (x + y)²(x-y)²
can someone explain me how to make it step by step?