10.D The third term of the sequence is 4 ÷ 2 =2.
The fourth term is 2 + 8 =10. The fifth term
is 10 ÷ 2 =5. The sixth term is 5 + 8 =13. The
seventh term is 13 ÷ 2 =6.5, which is the first
noninteger term.
11.D In this problem, only the signs of the terms
matter. The first term is negative and the second
is positive. The third term is ()(+) =. The
fourth term is (+)() =. The fifth term is
()() =+. The sixth term is ()(+) =. The first
six terms of the sequence are: ,+, , , +, .
The pattern , +, repeats every three terms. In
the first 90 terms, the pattern repeats 90 ÷ 3 = 30
times. Each repetition contains two negative
numbers, so in 30 full repetitions there are
30 × 2 =60 negative numbers.CHAPTER 11 / ESSENTIAL ALGEBRA 2 SKILLS 411