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 2 of 8.
Saniya said:
1 decade ago
The options are correct and even the answer is correct.
By adopting the formula {a+b} = a^2+2ab+b^2.
By adopting the formula {a+b} = a^2+2ab+b^2.
Abul said:
1 decade ago
Can anyone explain how (1-2a) instead of (2a-1) ?
Lokesh Ravella said:
1 decade ago
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).
4*a*a - 4*a + 1 can also be written as 1 + 4*a*a-4*a can be written as 1 + 4*a*a-2*a-2*a.
1 - 2*a + 4*a*a - 2*a.
Taking 1 as common in first two and 2*a in last two then 1(1 - 2*a)-2*a(1 - 2*a).
Hence (1 - 2*a)(1 - 2*a).
So Both Are Correct. So we have to choose any one of these such it satisfies the options available.
Taking 2*a common 2*a(2*a-1)-(2*a - 1).
Hence (2*a-1)(2*a-1).
4*a*a - 4*a + 1 can also be written as 1 + 4*a*a-4*a can be written as 1 + 4*a*a-2*a-2*a.
1 - 2*a + 4*a*a - 2*a.
Taking 1 as common in first two and 2*a in last two then 1(1 - 2*a)-2*a(1 - 2*a).
Hence (1 - 2*a)(1 - 2*a).
So Both Are Correct. So we have to choose any one of these such it satisfies the options available.
Shivam said:
1 decade ago
Not getting how can we take decision at exam time.
Barjinder singh said:
1 decade ago
Is there any other method to solve it?
Sujith said:
1 decade ago
We can use both (2a-1), (1-2a). Its just based on options they given.
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.
Ashit patel said:
1 decade ago
2a-1=1-2a?
Vishal said:
10 years ago
Since the value of a has been given in the question hence 2a-1 can't be square root since then the square root will be negative and options given as answers are positive. Hope you guys got it.
Siddharth said:
10 years ago
Both (1-2a)^2 and (2a-1)^2 are correct we need to see from the options which answer is available.
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