What is the value of 2x^2 - 2.4x - 1.7 for x = 0.7 ?

Question

What is the value of  2x^2 - 2.4x - 1.7  for  x = 0.7  ?

(A) -0.72
(B) -1.42
(C) -1.98
(D) -2.40
(E) -2.89

PareshGmat · Accepted Answer

Answer = D = -2.4

2x^2 - 12.4x - 1.7

2x(x - 1.2) - 1.7

Placing the value x = 0.7

2 . 0.7 (-0.5) - 1.7

-0.7 - 1.7

= -2.4

m3equals333 · Answer

/100
=-2.4
D

Bunuel · Answer

SOLUTION

What is the value of 2x^2 - 2.4x - 1.7 for x = 0.7 ?

(A) -0.72
(B) -1.42
(C) -1.98
(D) -2.40
(E) -2.89

2x^2 - 2.4x - 1.7 =

= 2*0.7^2 - 2.4*0.7 - 1.7 =

= 2*0.49 - 1.68 - 1.7 =

= -2.4 .

Answer: D.

nutshell · Answer

2(0.7)^2 - 2.4(0.7) - 1.7
= 2(0.49) - 1.68 - 1.7
= 0.98 - 1.68 - 1.7
= -2.4

Ans is (D)

BrainLab · Answer

2*49*10^(-2) - 24*7*10^(-2) - 170*10^(-2) = -240*10^(-2) = -2,4

Update
 x(2x-2,4)-1,7 = 0,7(1,4-2,4)-1,7 = -0,7-1,7=-2,4

Abhishek009 · Answer

2x^2  -  2.4x  - 1.7 ; given x = 0.7

Or,  2(0.7)^2  -  2.4(0.7)  -  1.7

Or,  2(0.49)  -  2.4(0.7)  -  1.7

Or,  0.98  -  1.68  -  1.7

Or,  - 2.40

Hence answer will be (D)

Himanshu9818 · Answer

The Official Guide For GMAT® Quantitative Review, 2ND Edition

What is the value of 2x^2 - 2.4x - 1.7 for x = 0.7 ?

(A) -0.72
(B) -1.42
(C) -1.98
(D) -2.40
(E) -2.89

2*0.7*0.7-2.4*0.7-1.7
.98-1.68-1.7
=-2. 40
answer D

bimalr9 · Answer

2 * \frac{7}{10}* \frac{7}{10}- 2.4 * \frac{7}{10}- 1.7

=  \frac{49}{50} - 2.4 * 10 *\frac{7}{10 * 10}- 1.7 * \frac{10}{10}

=  \frac{49}{50} - 24 *\frac{7}{100}- \frac{17}{10}

=  \frac{49}{50} - \frac{42}{25} - \frac{17}{10}

= \frac{98-168-170}{100}

= -2.4
=Answer D.

ScottTargetTestPrep · Answer

Substituting 0.7 for x, we have:

2(0.7)^2 - 2.4(0.7) - 1.7

2(0.49) - 1.68 - 1.7 = 0.98 - 1.68 - 1.7 = -2.4

Alternate Solution:

Let’s factor the expression 2x^2 - 2.4x - 1.7:

2x^2 - 2.4x - 1.7 = (x - 1.7)(2x + 1)

Now, substituting x = 0.7 in the factored expression, we get (0.7 - 1.7)(2(0.7) + 1) = (-1)(1.4 + 1) = -2.4.

Answer: D

dineshril · Answer

2x^2-2.4x-1.7
=> x(2x-2.4)+1.7
=> substituting x=0.7
=> 0.7(2*0.7-2.4)+1.7
=> 0.7(1.4-2.4)+1.7
=> 0.7(-1)+1.7
=> -0.7-1.7
=> -2.4

Therefore 'D'

Thanks
Dinesh

KanishkM · Answer

2x^2 - 2.4x - 1.7 , substitute x = 0.7

0.7 ( 1.4 - 2.4) - 1.7 
-0.7 - 1.7 
-2.40

D

mykrasovski · Answer

Gentlemen,

2x^2-2.4x-1.4 = (x-1.7)(x+0.5) = (0.7-1.7)(0.7+0.5) = -1.0 * 1.2 = -1.2

Where is my mistake?

Kinshook · Answer

Asked: What is the value of  2x^2 - 2.4x - 1.7  for  x = 0.7  ?

2x^2 - 2.4x - 1.7  for  x = 0.7  
= 2(.7)^2 - 2.4(.7) - 1.7
=2*.49 - 2.4*.7 - 1.7
= .98 - 1.68 - 1.7
= -.7 - 1.7 
= - 2.4

IMO D

Kinshook · Answer

mykrasovski

You factorisation is incorrect. In fact, there is no need for factorisation of the expression.
 2x^2-2.4x-1.4 
eq (x-1.7)(x+0.5)

mykrasovski · Answer

Kinshook correct, thanks for the remark. I do not really know what I was thinking when trying to factorize the expression....

Abhishek009 · Answer

2x^2 - 2.4x - 1.7

Or,  2x^2 - 3.4x + x - 1.7

Or,  2x (x - 1.7) + 1(x - 1.7)

Or,  (x - 1.7)(2x + 1)

Or,  (0.7 - 1.7)(2*0.7 + 1)

Or,  (-1)(2.14)

Or,  -2.40 , Answer must be (D)

8.toastcrunch · Answer

To find the value of the expression 2x^2 - 2.4x - 1.7 for x = 0.7,
Replacing x with 0.7 in the expression:

2(0.7)^2 - 2.4(0.7) - 1.7
Simplifying:
2(0.49) - 1.68 - 1.7
0.98 - 1.68 - 1.7

Combining like terms:
-0.7 - 1.7
-2.4
Therefore, Answer is

akshatcy · Answer

Let  2x^2  - 2.4x - 1.7 = Y
Substitute x = 0.7
2( \frac{7}{10} )( \frac{7}{10} ) - ( \frac{24}{10} )( \frac{7}{10} ) - ( \frac{17}{10} ) = Y

Multiply throughout by 100,
100Y = 14(7) - 24(7) - 10(17)
100Y = 7(14 - 24) - 170
100Y = - 70 - 170
100Y = - 240
Y = - 2.40

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What is the value of 2x^2 - 2.4x - 1.7 for x = 0.7 ?

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