# Aptitude - Square Root and Cube Root - Discussion

Discussion Forum : Square Root and Cube Root - General Questions (Q.No. 6)

6.

If *a* = 0.1039, then the value of 4*a*^{2} - 4*a* + 1 + 3*a* is:

Answer: Option

Explanation:

4*a*^{2} - 4*a* + 1 + 3*a*
= (1)^{2} + (2*a*)^{2} - 2 x 1 x 2*a* + 3*a*

= (1 - 2*a*)^{2} + 3*a*

= (1 - 2*a*) + 3*a*

= (1 + *a*)

= (1 + 0.1039)

= 1.1039

Discussion:

70 comments Page 2 of 7.
Pushpa said:
1 decade ago

While I am solving getting (2a-1) or we can write (1-2a) also but why answer differs I mean according to options we should change ?

Soumya said:
1 decade ago

Krishna nice explanation.

Rakesh. said:
1 decade ago

I do agree with krishan, however 2a-1 is not equal to 1-2a because the value may be the same however, is it postive or negitive value, so can anyone explain on this?

BhargaV said:
1 decade ago

4a2 - 4a + 1

(2a)2 - 2(2a)(1) + (1)2

(2a - 1)2

so, 2a - 1 + 3a

Why 1 - 2a is here ???

(2a)2 - 2(2a)(1) + (1)2

(2a - 1)2

so, 2a - 1 + 3a

Why 1 - 2a is here ???

Sayani said:
1 decade ago

I agree with those who has a doubt as why it won't be (2a-1)^2. should we change our ans according to the options available???

Mannoj kumar said:
1 decade ago

I agree with sayani. We need to see the options also.

Sid said:
1 decade ago

Who goes for the answer anyone solving this would go for the formula asq - 2ab + bsq which will give (2a - 1)sq.

I don't think (1-2a)sq can be the way out.

I don't think (1-2a)sq can be the way out.

Joginder said:
1 decade ago

I have the same doubt, why cant it be (2a-1)2.

Mithun said:
1 decade ago

sqrt(4a2-4a+1)=2a-1 or 1-2a?

Sudarsan said:
1 decade ago

Your ans is right. But according to KRISHNA ,the sqrt of (2a-1)^2 is +(2a-1) and -(2a-1).so if we choose -(2a-1) then we get

-(2a-1)+3a=-2a+1+3a

=a+1

=.1039+1=1.1039 (ans)

So, this is the technique to SATISFY the option, that has given in the question.

-(2a-1)+3a=-2a+1+3a

=a+1

=.1039+1=1.1039 (ans)

So, this is the technique to SATISFY the option, that has given in the question.

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