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What is the value of 4x^2 + 5x – 2 ?

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What is the value of 4x^2 + 5x – 2 ?  [#permalink]

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New post 15 Nov 2019, 02:37
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

51% (01:33) correct 49% (01:34) wrong based on 63 sessions

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Manager
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Concentration: General Management, Strategy
GMAT 1: 580 Q41 V28
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WE: Project Management (Energy and Utilities)
Re: What is the value of 4x^2 + 5x – 2 ?  [#permalink]

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New post 15 Nov 2019, 02:54
What is the value of \(4x^2 + 5x – 2\) ?


(1) \(4x^2 + 4x + 1 = 0\)

(2) \(x(4x + 5) = 2\)


Answer is A

(1) Solving equation, x =-1/2, Solution of the given equation cant be found
(2) we cant find value of x. INSUFFICIENT.
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Re: What is the value of 4x^2 + 5x – 2 ?  [#permalink]

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New post 15 Nov 2019, 08:21
What is the value of 4x2+5x–24x2+5x–2 ?


(1) 4x2+4x+1=04x2+4x+1=0

(2) x(4x+5)=2x(4x+5)=2


Answer is D

From Statement 1 we find x=-1/2 Hence value of 4x2+5x–24x2+5x–2 = -7/2

From Statement 2 we find value of equation = 0
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Re: What is the value of 4x^2 + 5x – 2 ?  [#permalink]

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New post 15 Nov 2019, 11:53
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1
Bunuel wrote:
What is the value of \(4x^2 + 5x – 2\) ?


(1) \(4x^2 + 4x + 1 = 0\)

(2) \(x(4x + 5) = 2\)


Are You Up For the Challenge: 700 Level Questions


From Statement - 1 : \(4x^2 + 4x + 1 = 0\)
It is of the form \(ax^2 + bx + c = 0\)
To find Roots, we use discriminant formula;
\(D = b^2 - 4ac\)
\(D = (4)^2 - 4(4)(1)\)
D = 16 - 16 = 0
This means roots are equal.

Hence we will have a unique value of 'x' and we can substitute the same in \(4x^2 + 5x – 2\) and find the equation's value.

Hence Sufficient

From Statement - 2 : \(x(4x + 5) = 2\)
Expanding equation :
\(4x^2 + 5x = 2\)
\(4x^2 + 5x - 2 = 0\)

equation's value = 0

Hence Sufficient

Therefore IMO answer is D
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Re: What is the value of 4x^2 + 5x – 2 ?  [#permalink]

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New post 19 Nov 2019, 12:40
Bunuel wrote:
What is the value of \(4x^2 + 5x – 2\) ?


(1) \(4x^2 + 4x + 1 = 0\)

(2) \(x(4x + 5) = 2\)


Are You Up For the Challenge: 700 Level Questions


Just a Note :

Both the statements are giving different answer values
From statement 1 we get x= -1/2 then \(4x^2 + 5x – 2\) = -3.5

Well as from statement 2 we get \(4x^2 + 5x – 2\) = 0

So both the statements are giving different values. This should not happen.
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Re: What is the value of 4x^2 + 5x – 2 ?   [#permalink] 19 Nov 2019, 12:40
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