Question

(t-1)(t+1)(t²+1)
= t⁴-1
But how

Answer 1

(t-1)(t+1) = t^2-1 through the difference of squares rule

So,

(t-1)(t+1)(t^2+1)

(t^2-1)(t^2+1)

(x-1)(x+1) ... let x = t^2

x^2-1 .... another application of the difference of squares rule

(t^2)^2 - 1... plug in x = t^2

t^4 - 1