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neokeynesian
11-07-2004, 08:29 AM
Which one is correct?

(2.sqrt(b))^2 =
a)2b
b)4b

(a) or (b) ?
I presume that (a) is the right answer. There is a question from PP that i posted recently in this forums (http://www.urch.com/forums/showthread.php?t=14807) using this concept i.e. (a) is the correct answer
anyone can explain?
is there any source from the web to refer fro this fundamental concept?

thanx

thebullfighter
11-07-2004, 09:07 AM
Which one is correct?

(2.sqrt(b))^2 =
a)2b
b)4b

(a) or (b) ?
I presume that (a) is the right answer.
Ouch!!!

(2.sqrt(b))^2 = 4(sqrt(b))^2 =4b

Or, let b be 9, sub. in..

(2.sqrt(b))^2= (2.sqrt(9))^2 = (2.3)^2 = 6^2 = 36

also, 36/b = 36/9 = 4
or, same as 4b = 36

Hence, 4b or choice (b)

danielman
11-07-2004, 04:41 PM
Which one is correct?

(2.sqrt(b))^2 =
a)2b
b)4b

(a) or (b) ?
I presume that (a) is the right answer.
If you can't remember the exponentiation rules, you only have to remember what to square a number means:

a^2 = a*a

so, (2.sqrt(b))^2 = (2.sqrt(b))(2.sqrt(b)) = (2.2)(sqrt(b).sqrt(b)) = 4b

hope this helps

777
11-07-2004, 08:39 PM
I got 4b as well.

(2 X sqrt(b))^2 =

2^2 X sqrt(b)^2 = 4b

neokeynesian
11-08-2004, 04:18 AM
Thanx to all of u.