I X I = positive. so, (-X . I X I) means (- (-). +) or positive. sqrt of positive is positive. IMO D.
Since x<0, let's say that x= -5
So, the sqrt[-x (|x|)] = sqrt[5 (|-5|)] = sqrt[5(5)] = sqrt = 5
Answer choice A is -x, so if x= -5, then -x = 5. Since our output above is 5, answer choice A is correct.
Hey 800, You have presupposed that x is negative, i.e -x and you are calculation leads to x, which is positive in sign. Hence you need -(-x )....
Even simpler, lets assume, x to be -y , you have SQRT ( -(-y) . | -y | ) = SQRT (y^2 ) = Y.... But what is y ??? -x..... Hence answer is A.
Thanks Brent for the explanation.
Yes I got the point !!! I missed the basic of roots!
Rule: a root can only have a negative value if 1. it is an odd root and 2. the base of the root is negative. Here I had to apply the second condition of the rule.
Thanks Brent & shyamprasadrao to inspire me to review the basic.
The square root of any number (by definition) is always positive (or zero in the case of sqrt(0)=0).
So, sqrt(100)=10, sqrt(49)=7, . . . etc.
There are currently 1 users browsing this thread. (0 members and 1 guests)