(5a^3-2a^2)+(6a^3+9a^2+8a)

11a^3 + 7a^2 + 8a

Step-by-step explanation:

( 5a^3 - 2a^2 ) + ( 6a^3 + 9a^2 + 8a )

= 5a^3 + 6a^3 + -2a^2 + 9a^2 + 8a

= 11a^3 + 7a^2 + 8a

the answer is:

the correct option is the option b.

to calculate the surface area of the right cylinder, we need to use the following formula:

from the picture we know that:

so, substituting and calculting we have:

hence, we have that the correct option is the option b.

have a nice day!