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# How many real roots does the polynomial 2x^3+8x-7 have?

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Manager
Joined: 13 Aug 2018
Posts: 58
How many real roots does the polynomial 2x^3+8x-7 have?  [#permalink]

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06 Dec 2019, 11:43
1
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Difficulty:

65% (hard)

Question Stats:

29% (01:11) correct 71% (01:08) wrong based on 31 sessions

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How many real roots does the polynomial 2x^3+8x-7 have?

A. none
B. One
C. Two
D. Three
E. Eight
VP
Joined: 19 Oct 2018
Posts: 1290
Location: India
How many real roots does the polynomial 2x^3+8x-7 have?  [#permalink]

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06 Dec 2019, 13:16
f(0)=-7
f(1)= 3

There must be 1 or 3 roots of the equation in interval 0 to 1

derivative of $$f(x)= 6x^2+8$$ is positive for all real values of x.

Hence there is only 1 solution possible.

Not a GMAT Question tho.

jackfr2 wrote:
How many real roots does the polynomial 2x^3+8x-7 have?

A. none
B. One
C. Two
D. Three
E. Eight
How many real roots does the polynomial 2x^3+8x-7 have?   [#permalink] 06 Dec 2019, 13:16
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