Answer:

3^9 + 2 × 3^8 - 5 ×3^8

Taking 3^8 comman

3^9 + 3^8 ( 2-5 )

3^9 + 3^8 ( -3)

we can write -3 as -3^1

3^9 + 3^8 × -3^1

and we know m^a × m^b = m^(a +b)

3^9 + (-3)^9

= 0