# Math Help - Factorising a cubic.

1. ## Factorising a cubic.

Hi

I have a question about algebra

for example 8t^3 - 27 how to convert to this model

(2t - 3)(4t^2 + 6t + 9)

2. Originally Posted by ehsangha
Hi

I have a question about algebra

for example 8t^3 - 27 how to convert to this model

(2t - 3)(4t^2 + 6t + 9)
It is the difference of two cubes formula

$(a\pm b)^3 = (a \pm b)(a^2 \mp ab + b^2)$

$8t^3-27 = (2t)^3-3^3$