csat-suneung 2021 Q18

csat-suneung · South-Korea · csat__math-science 4 marks Curve Sketching Continuity and Discontinuity Analysis of Piecewise Functions
For a constant $a$, define the function $f ( x )$ as $$f ( x ) = \lim _ { n \rightarrow \infty } \frac { ( a - 2 ) x ^ { 2 n + 1 } + 2 x } { 3 x ^ { 2 n } + 1 }$$ What is the sum of all values of $a$ such that $( f \circ f ) ( 1 ) = \frac { 5 } { 4 }$? [4 points]
(1) $\frac { 11 } { 2 }$
(2) $\frac { 13 } { 2 }$
(3) $\frac { 15 } { 2 }$
(4) $\frac { 17 } { 2 }$
(5) $\frac { 19 } { 2 }$
For a constant $a$, define the function $f ( x )$ as
$$f ( x ) = \lim _ { n \rightarrow \infty } \frac { ( a - 2 ) x ^ { 2 n + 1 } + 2 x } { 3 x ^ { 2 n } + 1 }$$
What is the sum of all values of $a$ such that $( f \circ f ) ( 1 ) = \frac { 5 } { 4 }$? [4 points]\\
(1) $\frac { 11 } { 2 }$\\
(2) $\frac { 13 } { 2 }$\\
(3) $\frac { 15 } { 2 }$\\
(4) $\frac { 17 } { 2 }$\\
(5) $\frac { 19 } { 2 }$