2 problems I am not sure about, please help!!

Alice07 said:

Instruction:Multiply and Simplify
(2a)exponent 2 multiplied by (2a)exponent 6

\(\displaystyle (2\cdot a)^2\cdot (2\cdot a)^6\)

\(\displaystyle = \, (2\cdot a)^8\)

\(\displaystyle = \, 256\cdot a^8\)
I have 2 answers that I have come up with, 256exponent 8 or is it (4a)exponent 8
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Instruction: Simplify

3(x exponent 2)exponent 3(-2x exponent 4) exponent 2
I have come up with the answer 12x exponent 14, is this correct?

Thank you for your help!!

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