Answer:
a = 5
Step-by-step explanation:
Hello, please consider the following.
[tex]6x^3+18x^2-240x=6x(x^2+3x-40)\\\\\text{** The sum of the zeroes is -3=-8+5 and the product is -40=-8*5. **}\\\\\text{** So, we can factorise. **}\\\\6x^3+18x^2-240x=6x(x^2+3x-40)=6x(x^2+8x-5x-40)\\\\=6x(x(x+8)-5(x+8))\\\\\large \boxed{=6x(x+8)(x-5)}[/tex]
So, a = 5.
Thank you.