If a = 1 and (a - b)/c = 1 which of the following is NOT a possible va

Question

If a = 1 and (a - b)/c = 1 which of the following is NOT a possible value of b?

A. -2
B. -1
C. 0
D. 1
E. 2

Bunuel · Accepted Answer

If a=1 and (a-b)/c = 1 which of the following is NOT a possible value of b?

A. -2
B. -1
C. 0
D. 1
E. 2

First of all remember that division by zero is undefined, hence  c
eq{0}  and that's why you CAN cross-multiply.

\frac{a-b}{c}=1

Since  a=1 , then

\frac{1-b}{c}=1 ;

1-b=c

But since  c
eq{0} , then  1-b
eq{0} , thus  b
eq{1} .

Answer: D.

Hope it's clear.

LM · Answer

b = (1-c)

If b=1, then C=0, which will not satisfy (a-b)/c = 1. ( divisibility by 0 is not possible.)

therefore b=1 is not possible.

eschn3am · Answer

Equation is:

(a-b)/c = 1 where a = 1

so plug in 1 for a and look at it again

(1-b)/c = 1

now C can be anything we want, so if b = -2 we can plug it in and make it work

(1-(-2))/c = 1
3/c = 1
c = 3 and it works

HOWEVER, if we have a 0 in the numerator there isn't a number on earth that makes 0/C = 1

(1-1)/c = 1
0/c = 1
there aren't any matches for C to make this true

B cannot be 1.

Answer is D

imhimanshu · Answer

Hi. 
Can anyone let me know what is wrong in my approach -

(a-b)/c = 1

a-b = c(by cross multiplying)
Now as a= 1
1-b = c
implies, 1-c=b
Now c can take any value, and b can have any of the values provided in the answer choices. Please let me know where I am going wrong. Why it is not possible to cross multiply in the first instance. this is how I approached in my exam.

Thanks

amanvermagmat · Answer

If a=1, then (a-b)/c = (1-b)/c which is given to be = 1

Obviously b cannot be equal to 1, because then (1-b) will become 0, which is not possible.

Hence  D answer

JeffTargetTestPrep · Answer

If a = 1, we have:
 
(1 - b)/c = 1
 
1 - b = c
 
We must also remember that since (1 - b)/c = 1, and since dividing by zero creates an undefined result, c cannot be zero.
 
Let’s test the answer choices:
 
A) -2
 
Since c = 1 - (-2) = 3, b could be -2.
 
B) -1
 
Since c = 1 - (-1) = 2, b could be -1.
 
C) 0
 
Since c = 1 - 0 = 1, b could be 0.
 
D) 1
 
Since c = 1 - 1 = 0, b cannot be 1.
 
Alternate Solution:
 
If a = 1, we have:
 
(1 - b)/c = 1
 
1 - b = c 
 
The original equation had c in the denominator, so we know that c cannot equal 0. The value of b that makes c = 0 is b = 1. Thus, b cannot equal 1.
 
Answer: D

nishantswaft · Answer

Bunuel

Can we think this way that, since a-b=c or 1-b=c
then, 1-c=b or  1-c/b=1

Since division by 0 is not defined value of b can't be zero?

Bunuel · Answer

No. b could be 0. For example, a = 1, b = 0, and c = 1. When from 1 - c = b, you divide by 0, you are already violating the division by 0 rule by dividing by b, which could be 0.

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If a = 1 and (a - b)/c = 1 which of the following is NOT a possible va

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If a = 1 and (a - b)/c = 1 which of the following is NOT a possible va

Prep Toolkit

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