Answer:
Step-by-step explanation:
First off, I think you should send this to your teacher because none of the answers are right. It should be 21v^7 BUT you should guess 14v^7 because maybe your teacher did their multiplication wrong and did 2v^3 * 7v^4.
When you multiply you add the exponents so v^3 * v^4 = v^7
since 3+4= 7
Then you multiply the other numbers like normal 3*7 =21
so 21v^7 BUT I would answer 14v^7 cause I think your teacher probably meant 2v^3*7v^4
