# 005 Sample Final A, Question 16

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${\displaystyle -x^{2}+4y^{2}-2x-16y+11=0}$
a) False. Nothing in the definition of a geometric sequence requires the common ratio to be always positive. For example, ${\displaystyle a_{n}=(-a)^{n}}$
c) False. ${\displaystyle y=x^{2}}$ does not have an inverse.
d) True. ${\displaystyle cos^{2}(x)-cos(x)=0}$ has multiple solutions.