Find the balance in the account after the given period $4,700 deposit earning 4.2% compound monthly, after 2 years

Equation:
A = P(1 + rt)

First, converting R percent to r a decimal
r = R/100 = 4.2%/100 = 0.042 per year.

Putting time into years for simplicity,
24 months / 12 months/year = 2 years.

Solving our equation:
A = 4700(1 + (0.042 × 2)) = 5094.8 
A = $5,094.80

The total amount accrued, principal plus interest, from simple interest on a principal of $4,700.00 at a rate of 4.2% per year for 2 years (24 months) is $5,094.80.
$5,094.80 is the answer.

The vertex of the quadratic function is (1.5, -.75)