Question 132593
let x=interest rate


15569.75=10000(1+x)^2+3500(1+x) __ 15569.75=10000(1+2x+x^2)+3500+3500x


dividing by 10000 __ 1.556975=1+2x+x^2+.35+.35x


subtracting 1.556975 __ 0=x^2+2.35x-.206975


using quadratic formula __ x=(-2.35ħsqrt(2.35^2-4(-.206975)))/2


x=.085 or 8.5%