How do you factor y^4 - 1?

y^4 - 1 is a difference of two squares,

it is in the form a² - b²,

it factors into the form (a + b)(a - b)

If a² is y^4, then a is y² {the square root of y^4}

If b² is 1, then b is 1 {the square root of 1}

y^4 - 1

= (y² + 1)(y² - 1) {factored the difference of two squares into two binomials}

=

it is in the form a² - b²,

it factors into the form (a + b)(a - b)

If a² is y^4, then a is y² {the square root of y^4}

If b² is 1, then b is 1 {the square root of 1}

y^4 - 1

= (y² + 1)(y² - 1) {factored the difference of two squares into two binomials}

=

**(y² + 1)(y + 1)(y - 1)**{y² - 1 was also a difference of two squares, as before}*© Algebra House*