Find the 9th term of the geometric sequence 9, -27, 81,
1 answer:
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Answer:
• x = -4, x = 0, x = 1
Step-by-step explanation:
x is a factor of all terms, so x=0 is a zero. (Eliminates choices 1 and 5.)
The sum of coefficients is 0, so x=1 is a zero. (Eliminates choices 3 and 4.)
Reversing the sign of the odd-degree terms gives signs of -++, so there is one sign change, hence one negative real root (by Descartes' rule of signs). This confirms choice 2 as the answer.
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Of course, your graphing calculator can answer this almost as quickly.
