The parabola
intersects the graph of
at four distinct points. These four points on a same circle. Find the value of
.
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Suppose the equation of the circle is ( x − h ) 2 + ( y − k ) 2 = r 2
Since it intersects with the graph f ( x ) = x 2 , the above equation can be rewritten as ( x − h ) 2 + ( x 2 − k ) 2 = r 2
Note that the coefficient of x 3 of above quartic equation is 0.
Let the x -coordinates of 4 intersection points be α 1 , α 2 , α 3 and α 4 . Then α 1 + α 2 + α 3 + α 4 = 0 . On the other hand, from g ( x ) = x 4 + a x 3 − 2 x 2 + b x + 1 , the sum of roots is − 1 a . So a = 0 and hence ⌊ 1 0 0 0 a b ⌋ = 0 .