Answer:
Step-by-step explanation:
d=21-15=6
recursive formula is

C must equal 5
<span>-2x^3(5x^3+x^2)= -10x^6 - 2x^5
answer
c = 5
</span>
Hey there! I'm happy to help!
First let's combine all of the terms with a.
2a+2a=4a
Now the ones with b.
3b-b=2b
And the ones with c.
-4c+2c=-2c
So, our simplified expression is 4a+2b-2c.
Have a wonderful day! :D