Daily Regents: Factoring and Compound Interest

I'll be reviewing a New York State Regents Exam Question every day from now until the Regents exams begin next month. At least, that is the plan.

August 2014, Questions 25 and 26

25. In the equation x² + 10x + 24 = (x + a)(x + b), b is an integer. Find algebraically all possible values of b.

x² + 10x + 24 factors into (x + 4)(x + 6), the order of the two binomials doesn't matter.
So the possible values of b are 4 and 6.

26. Rhonda deposited $3000 in an account in the Merrick National Bank, earning 4.2% interest, compounded annually. She made no deposits or withdrawals. Write an equation that can be used to find B, her account balance after t years.

The formula you need is B = P(1 + r)^t
P = 3000, the principal, or starting amount
r = .042, which is 4.2% as a decimal
t is time. No specific value is given, so use the variable.

That makes the answer B = 3000(1.042)^t

Any questions?

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