Answer:
-8y^7 - 5y^6 + 9y^5 + 3y^4 - 4y^3
Explanation:
Please be sure to use " ^ " to indicate exponentiation. Then,
your 9y5−4y3−8y7−5y6+3y4 becomes 9y^5 - 4y^3 - 8y^7 - 5y^6 + 3y^4.
We must now write that in descending order by powers of y:
-8y^7 - 5y^6 + 9y^5 + 3y^4 - 4y^3