
On page 669 of the Precalculus textbook, I think there is a slight mistake in the equality at the top of the page.
The middle and right side of the equalities have "n+1" as the exponent of 10.
I think BOTH these exponents should be "n" instead.
Sum[k=1 to n] 9/10^k = 1  1/10^n should be the correct expression.
Equation 9.2 (page 666) is correct, but I think a slight mistake has been made in applying it on page 669, by mixing which of the two expressions in 9.2 we are using.
As an example, we know that
Sum[k=1 to 2] 9/10^k = 9/10 + 9/100 = 0.9 + 0.09 = 0.99
If we use the existing expression on page 669, we get
Sum[k=1 to 2] 9/10^k = 1  1/10^(n+1) = 1  1/10^(2+1) = 1  /10^3 = 0.999 which is incorrect.
On the other hand,
Sum[k=1 to 2] 9/10^k = 1  1/10^n = 1  1/10^2 = 1  1/100 = 0.99 is correct.
I think the "n+1" in the equation at the top of page 669 as well as in the short paragraph following the equation should be changed to "n"
Thank you.
