Aptitude - Decimal Fraction - Discussion

Discussion :: Decimal Fraction - General Questions (Q.No.3)

3. 

The value of (0.96)3 - (0.1)3 is:
(0.96)2 + 0.096 + (0.1)2

[A]. 0.86
[B]. 0.95
[C]. 0.97
[D]. 1.06

Answer: Option A

Explanation:

Given expression
= (0.96)3 - (0.1)3
(0.96)2 + (0.96 x 0.1) + (0.1)2
= a3 - b3
a2 + ab + b2
= (a - b)
= (0.96 - 0.1)
= 0.86

Vignesh said: (Feb 12, 2011)  
Please tell how (a-b) is possible

Gokil said: (Feb 26, 2011)  
How (a-b) possible? please tell.

Shivakarthik said: (Mar 25, 2011)  
The formula for a cube - b cube is (a-b)(a2+ab+b2) this 2 s are squares so we cancel the denominator we get (a-b).

Hope you understand.

Akshu said: (Jul 27, 2011)  
Can tell me clearly please I didn't get.

Jasmine said: (Sep 20, 2011)  
Hi friends,

(0.96)3-(0.1)3/(0.96)2+0.096+(0.1)2

a3-b3/a2+ab+b2 = (a-b)(a2+ab+b2)/(a2+ab+b2) = (a-b)
so a=0.96 and b=0.1

(a-b)=0.96-0.10= 0.86

Kannan said: (Feb 3, 2012)  
How a-b possible ?

Nathi said: (Sep 8, 2012)  
How is it possible?

Nathi said: (Sep 8, 2012)  
Hi Friends,

Formula

(a^3-b^3) = (a-b)(a^2+ab+b^2)/a^2+ab+b^2

So cancel thes and we get (a-b).

Bhumi said: (Sep 18, 2012)  
How is it possible a-b?

Rajiv Kumar said: (Apr 3, 2013)  
We know that (a-b) ^3= (a-b) (a^2+ab+b^2) now in denominator (a^2+ab+b^2) is already given so we cancel these term we get (a-b).

Harish said: (Jul 1, 2014)  
What is formula for:

a^3-b^3 = (a-b)(a^2+b^2+ab).

You got it now we have from question.

a-b = (a^3-b^3)/(a^2+ab+b^2).

LHS = RHS.

So we LHS.

a-b = 0.96-0.1

= 0.86.

M.Azam said: (Jan 24, 2015)  
@Vineash.

The formula of a^3-b^3 = (a-b)(a^2+ab+b^2).
Hence a^3-b^3/a^2+ab+b^2 = a-b.

Annie Sethi said: (Jul 9, 2016)  
Given expression
=(0.96)3 - (0.1)3.
(0.96)2 + (0.96 x 0.1) + (0.1)2.

as The formula is

a3 - b3
-----------
(a2 + ab + b2)

So, open this formula of a3 - b3 => (a - b) (a2 + ab + b2)

Then,
(a - b) (a2 + ab + b2)
------------------------------
(a2 + ab + b2)

Cancel the alike terms and yu will get;
= (a - b)
= (0.96 - 0.1)
= 0.86.

Anandhan said: (Nov 27, 2016)  
But (a + b)3 is = (a - b) (a2 + ab + b2). Here a3 + b3 so how it can be possible? Both are different, Right?

Sachin Pal said: (Jan 10, 2017)  
As we have formula a3-b3 = (a-b)(a2+ab+b2).

Now,
(a2+ab+b2) is cancel out and we have (a-b)only.
So, .96 -.1 = .86.

Kinyera said: (Apr 30, 2017)  
@ALL.

Just expand (a-b)^3 in the middle somewhere you will get (a^3-b^3), make it the subject.

This must make you understand how a3-b3 = (a-b)(a2+ab+b2) came about.

Sadhuru said: (Jul 21, 2017)  
How to solve ab? Please explain it for me.

Abhiram said: (Dec 6, 2017)  
We multiply (0.96-0.1) on both numerator and denominator and alike terms are cancelled and we get an answer.

0.96-0.1=0.86.

Haritha said: (Dec 25, 2017)  
a3-b3/a2+ab+b2 = (a3-b3)/(a2+b2)+ab is not equal to a-b.

The denominator will cancel the numerator as both are products of a-b.
ie;it will leave the answer a-b/ab.

Tinkeee said: (Apr 20, 2018)  
No, the correct way to get a^3-b^3 you have to multiply a^2 - ab - b^2 by a-b. We want to get a^3-b^3.

So why are we finding (a^3-b^3) / (a^2+ab+b^2) ? Actual answer is 0.88 not 0.86.

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