Answer: 
Step-by-step explanation:

I believe the answer is 84x.
1. Combine the like terms which is 4x, 8x, and 8x.
2. Add them and you’ll get 84x.
Answer:
The number that would go in the blank to get a perfect square trinomial is 18
Step-by-step explanation:
The middle term can always be found by taking twice of the square root of the final term.
2 * √81 = 18
Answer:
Principal = 3500
Time = 8 years
We are given that compound quarterly
So, No. of compounds per year = 2
Rate of interest = 5%
Formula : 
Substitute the values :


Interest = 3863.345 - 3500 = 363.345
Hence the total amount in an investment of $3500 that was compounded quarterly for 8 years at a rate of 5% is $3863.345 and the interest that was made on that account mentioned is $363.345