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nicole
01-06-2014, 11:33 AM
x-intercepts SAT Subject test Math level 2

How many x-intercepts has the graph of f(x)=3x^-x^3+6x^2+5x-2 ?

(A) 0
(B) 1
(C) 2
(D) 3
(E) 4

Thanks!

miranda
01-06-2014, 11:34 AM
This is a GDC (graphic display calculator) question.

For example in CASIO fx-9860 we have to do the following procedure in order to find the real roots (x-intercepts) of this graph.
MENU>GRAPH>Y1=3x^-x^3+6x^2+5x-2 >DRAW(F6)
We observe that the graph of f has two x-intercepts at x=0.8315131 \ or \
x=0.29567535

Therefore the correct answer is (C)

Hope these help!!

nicole
01-06-2014, 11:35 AM
Thanks miranda!:)