Question

What is 12x squared - 9x + 15

Answer 1

$12x^2 - 9x + 15 = 3(4x^2-3x+5)$

Answer 2

12x² - 9x + 15

It can be written as . . .

3 ( 4x² - 3x + 5 )

but that's just a different way to write the same thing. It doesn't
tell you anything new, until you know what number 'x' is.