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# When 3x^2 + nx + 5 = 0 has only one solution, n=?

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Manager
Joined: 28 May 2018
Posts: 150
Location: India
Schools: ISB '21 (A)
GMAT 1: 640 Q45 V35
GMAT 2: 670 Q45 V37
GMAT 3: 730 Q50 V40
When 3x^2 + nx + 5 = 0 has only one solution, n=?  [#permalink]

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17 Mar 2019, 10:54
5
00:00

Difficulty:

25% (medium)

Question Stats:

72% (01:18) correct 28% (02:04) wrong based on 64 sessions

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When $$3x^2 + nx + 5 = 0$$ has only one solution, n=?

A) $$\sqrt{48}$$
B) $$\sqrt{80}$$
C) $$10$$
D) $$3\sqrt{2}$$
E) $$\sqrt{60}$$
Manager
Joined: 21 Feb 2019
Posts: 125
Location: Italy
Re: When 3x^2 + nx + 5 = 0 has only one solution, n=?  [#permalink]

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17 Mar 2019, 11:00
2
If it has only one root, $$b^2 - 4ac = 0$$. Hence, $$n^2 - 4*3*5 = 0$$; $$n = \sqrt{60}$$.
Intern
Joined: 01 Jul 2019
Posts: 10
Re: When 3x^2 + nx + 5 = 0 has only one solution, n=?  [#permalink]

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21 Jul 2019, 22:33
lucajava wrote:
If it has only one root, $$b^2 - 4ac = 0$$. Hence, $$n^2 - 4*3*5 = 0$$; $$n = \sqrt{60}$$.

Is this just basic application of the quadratic formula? It looks different than the quadratic I normally see.
Re: When 3x^2 + nx + 5 = 0 has only one solution, n=?   [#permalink] 21 Jul 2019, 22:33
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