if d>0 and 0<1-c/d<1, which of the following must be true?
I. c>0
II. c/d<1
III. c^2 + d^2 > 1
a. I only
b. II only
c. I and II only
d. II and III only
e. I, II, and III
Answer is C
d>0
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- ssmiles08
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Answer should be (C).ST wrote:if d>0 and 0<1-c/d<1, which of the following must be true?
I. c>0
II. c/d<1
III. c^2 + d^2 > 1
a. I only
b. II only
c. I and II only
d. II and III only
e. I, II, and III
Answer is C
A) If d > 0, c should also be (+) b/c 1-(-c/d) will give you something greater than 1, which does not follow the requirement 0<1-c/d<1.
B) c/d should be < 1 b/c if they are greater than 1: 1-(c/d) will result in a negative number which does not follow the requirement 0<1-c/d<1.
C) does not have to be necessarily true: suppose c = 1/4, d = 1/2
c/d = 1/2 which is in b/w 0<1-c/d<1.
But (1/4)^2 + (1/2)^2 = 1/16 + 1/4 = 5/16 < 1
Therefore C does not hold true.
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Ok lets try to deconfuse you:)ST wrote:I am still confused....
d>0 and 0<1-c/d<1
0<1-c/d<1
here I am sure you would agree that 0<c/d<1, because if you subtract something from 1 and the result is between 0 and 1, the subtracted part must be between 0 and 1
in other words,
0<1-c/d<1
subtract 1 from all the terms
-1<-c/d<0
or, 1>c/d>0
d>0
so c must be >0
so I and II are true
now C and D are >0 but not necessarily >1
so if they are fractions then C^2+D^2 is not always >1
take the example of c=1/888080808080 and d=1/23728378787
The powers of two are bloody impolite!!