Answer: 378x^7
Step-by-step explanation
Multiply the coefficients to get 6*7*9 = 378. This is the coefficient of the final answer.
The x terms will have their exponents added up: 3+2+2 = 7. This is the exponent of the final answer over the x. The rule I'm using is a^b*a^c = a^(b+c)
That's how we end up with 378x^7