1. ## Not understanding polynomials

I do know what a polynomial is..... but this problem I don't understand

( y2-3y+6) (y1-3y2+y3) =

y3+y2-3y2-3y+y+6 =

Why does the above equal y3-2y2-2y+6? I know you have to combine the like terms, Like terms are like y2 - 3y2 Right???
How are they adding the like terms, these are the steps I'm not understanding.

2. Originally Posted by Leona_Marie
I do know what a polynomial is..... but this problem I don't understand

( y2-3y+6)+ (y1-3y2+y3) =

y3+y2-3y2-3y+y+6 =

Why does the above equal y3-2y2-2y+6? I know you have to combine the like terms, Like terms are like y2 - 3y2 Right???
How are they adding the like terms, these are the steps I'm not understanding.
Hello Leona,

You left out an important operator in your original expression. I assume you want to add these two polynomials together.

Your first step is correct: $y^3+y^2-3y^2-3y+y+6$

And you are correct about combining like terms. So let's group them together.

$y^3+(y^2-3y^2)+(-3y+y)+6$

Combining the terms in parentheses, we arrive at

$y^3-2y^2-2y+6$

as expected.

3. Thankyou for your quick reply, It helped me understand. I thought that like terms were like y x w. Im very new to this.