csat-suneung 2015 Q14

csat-suneung · South-Korea · csat__math-A 4 marks Stationary points and optimisation Count or characterize roots using extremum values

For the function $f ( x ) = x ( x + 1 ) ( x - 4 )$, answer the following. When the line $y = 5 x + k$ and the graph of the function $y = f ( x )$ intersect at two distinct points, what is the value of the positive number $k$? [4 points]
(1) 5
(2) $\frac { 11 } { 2 }$
(3) 6
(4) $\frac { 13 } { 2 }$
(5) 7

For the function $f ( x ) = x ( x + 1 ) ( x - 4 )$, answer the following.\\
When the line $y = 5 x + k$ and the graph of the function $y = f ( x )$ intersect at two distinct points, what is the value of the positive number $k$? [4 points]\\
(1) 5\\
(2) $\frac { 11 } { 2 }$\\
(3) 6\\
(4) $\frac { 13 } { 2 }$\\
(5) 7

Paper Questions

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