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 4a2 - 4a + 1 + 3a is:
Answer: Option
Explanation:
4a2 - 4a + 1 + 3a = (1)2 + (2a)2 - 2 x 1 x 2a + 3a
= (1 - 2a)2 + 3a
= (1 - 2a) + 3a
= (1 + a)
= (1 + 0.1039)
= 1.1039
Discussion:
71 comments Page 3 of 8.
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.
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 ?
Zareena said:
9 years ago
(1 - 2a)2 is wrong because if you expand it give 4a^2 + 4a + 1 which is not matching with the question.
So, - 0.4805 is the right answer.
So, - 0.4805 is the right answer.
Latha said:
1 decade ago
a2-2ab+b2 = 4a2-4a+1.
(a-b)2 it is in the form.
Where a=(2a), b=1.
So, (1-2a)2.
4a2-4a+1^2 = 1-2a^2.
1-2a+3a = a+1.
0.1039+1 = 1.1039.
(a-b)2 it is in the form.
Where a=(2a), b=1.
So, (1-2a)2.
4a2-4a+1^2 = 1-2a^2.
1-2a+3a = a+1.
0.1039+1 = 1.1039.
Bhavuk Singh said:
9 years ago
Given , a = 0.1039
2a - 1= 2(0.1039) - 1 = - .7922.
The square root of a negative number is not a real number. Hence, we use (1 - 2a).
2a - 1= 2(0.1039) - 1 = - .7922.
The square root of a negative number is not a real number. Hence, we use (1 - 2a).
Sintu Kumar said:
8 years ago
@Krishna.
But, my factor is (2a-1)(2a-1).
Than 2a-1+3a,
=5a-1,
=5*0.1039-1.
=0.5195-1=-0.4805.
But, my factor is (2a-1)(2a-1).
Than 2a-1+3a,
=5a-1,
=5*0.1039-1.
=0.5195-1=-0.4805.
(1)
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 ?
Mukesh Chauhan said:
5 years ago
Two answers are possible here.
One is: 2a-1 and 1-2a because the square of both numbers are the same.
Anyone, please clear this.
One is: 2a-1 and 1-2a because the square of both numbers are the same.
Anyone, please clear this.
(19)
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???
Shubham bansal said:
1 decade ago
Ok here we could check options but think if in any test both the answers are given then with which we have to go with.
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