What is the factorization of the trinomial below 3x^3-24x^2+45x

a. 3(x-3)(x+5)

b. 3(x^2-3)(x+5)

c. 3x(x-3)(x-5)

d. 3x(x-3)(x-5)

1st factor is 3x: 
= 3x(x² - 8x + 15) 

2nd & 3rd factors: 
x² - 8x + 15 = 0 
x² - 4x = - 15 + (- 4)² 
x² - 4x = - 15 + 16 
(x - 4)² = 1 
x - 4 = 1 

= x - 4 - 1, = x - 5 
= x - 4 + 1, = x - 3 

3x(x - 5)(x - 3) are the factors. 

Proof: 
= 3x(x - 5)(x - 3) 
= 3x(x² - 5x - 3x + 15) 
= 3x(x² - 8x + 15) 
= 3x³ - 24x² + 45x