Nkeiruka, we do this just like we do long division with whole numbers. Let's see what we can come up with.
First, we have to put things in order: 12y^3 + 12y^2 - 39y +15
How many times does 2y go into 12y^3? 6y^2, right? 6y^2(2y+5)= 12y^3+30y^2.
12y^3 - 12y^2
- 12y^3 +30y^2
______________
-18y^2
Bring down the -39y, so you have -18y^2 - 39y. How many times does 2y go into -18y? -9y, right? -9y(2y+5)= -18y^2-45y
-18y^2 - 39y
- -18y^2 - 45y
______________
6y
Bring down the 15 to make 6y+15
How many times does 2y go into 6y? 3, so 3(2y+5)= 6y+15
6y + 15
- 6y + 15
__________
0
You final answer is 6y^2 - 9y + 3.
Check your answer and do the same for the second problem.