Question

Over two summers, Ray saved $800.00 and $600.00. The polynomial represents his savings at the beginning of the third year, where x is the growth factor. (The interest rate r is x – 1.) What is the interest rate he needs to save $1,650.00 after the third summer?

800x2 + 600x

Answer 1

So at the end of the third year, it would be 800 x^3 + 600x^2? And he doesn't work the third summer? Then 800x^3 + 600x^2 = 1650 x = 1.0657758228... so he needs an interest rate of 6.57758.... % compounded annually.