# 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 1 of 7.
Bujji said:
1 decade ago

How we get the formula. I can't understand, give me the clarification about it.

Sundar said:
1 decade ago

Formula: a

^{2}+ b^{2}- 2ab = (a - b)^{2}
Sarath said:
1 decade ago

But I get (a-1/2) using (-b + -sqrt (b2 - 4ac) /2a).

Mitz said:
1 decade ago

In this case ans. Can also proceed with (2a - 1)^2 ??? Plz clarify !!

Krishna said:
1 decade ago

Sorry you are wrong

4*a*a - 4*a + 1 can be written as

4*a*a - 2*a -2*a +1

Taking 2*a common

2*a(2*a-1) -(2*a - 1)

Hence (2*a-1)(2*a-1) but it is given as (1-2*a)(1-2*a) is completely wrong how can he get that ????

If im wrong please explain me ???

4*a*a - 4*a + 1 can be written as

4*a*a - 2*a -2*a +1

Taking 2*a common

2*a(2*a-1) -(2*a - 1)

Hence (2*a-1)(2*a-1) but it is given as (1-2*a)(1-2*a) is completely wrong how can he get that ????

If im wrong please explain me ???

Nikhil said:
1 decade ago

The formula => a2 + b2 - 2ab = (a - b)2 can be

a2 + b2 - 2ab = (b - a)2 as well. so we can get it as (2a - 1) +3a . Then the answer will be different.

a2 + b2 - 2ab = (b - a)2 as well. so we can get it as (2a - 1) +3a . Then the answer will be different.

DhILDAS said:
1 decade ago

FOMULA (a-b) 2 is ok. But how square has gone from (1-2a) 2 and it written as (1-2a) +3a.

Mariappan said:
1 decade ago

Square root(a*a)=a

similarly square root{(1-2a)*(1-2a)}=1-2a

but my doubts is that why can't be (2a-1)

Can any one help with this problem ?

similarly square root{(1-2a)*(1-2a)}=1-2a

but my doubts is that why can't be (2a-1)

Can any one help with this problem ?

Tanvi said:
1 decade ago

Yes, Mariapan,

I agree with you.

Why it's not (2a-1)?

I agree with you.

Why it's not (2a-1)?

Rahul said:
1 decade ago

+*- = -

Then how it bcmz (1-2a)+3a = 1+a ?

Anyone can tell?

Then how it bcmz (1-2a)+3a = 1+a ?

Anyone can tell?

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