please help math factor trinomial
posted by Adriana .
y^313y^2+36y
Can someone please show me step by step that way I can understand. Thank you

first notice that you can factor out the y, leaving
y(y^213y+36)
Now you want two numbers that add to 13 and multiply to 36. Obviously they must both be negative. Easy factors of 36 are
1,36 2,18 3,12 4,9
It's clear that we want 4 and 9, so our polynomial is
y(y4)(y9)
This factoring by inspection is mainly a skill acquired by doing a lot of problems, so you get to recognize likely factors. 
Thank you soo much.. I have a lot of trouble with factoring