# Aptitude - Surds and Indices - Discussion

Discussion Forum : Surds and Indices - General Questions (Q.No. 2)

2.

If | a |
x - 1 |
= | b |
x - 3 |
, then the value of x is: |
||||

b |
a |

Answer: Option

Explanation:

Given | a |
x - 1 |
= | b |
x - 3 |
|||

b |
a |

a |
x - 1 |
= | a |
-(x - 3) |
= | a |
(3 - x) |
|||||||

b | b | b |

*x* - 1 = 3 - *x*

2*x* = 4

*x* = 2.

Discussion:

26 comments Page 1 of 3.
URVASHI said:
4 years ago

Simply Cross Multiply them a with a and b with b.

It becomes;

[a ^(x-1) ][a^(x-3)] = [b^(x-1)][b^(x-3)].

Power will get add on both sides.

Then,

a^(2x-4) = b^(2x-4),

Simply, x=2.

It becomes;

[a ^(x-1) ][a^(x-3)] = [b^(x-1)][b^(x-3)].

Power will get add on both sides.

Then,

a^(2x-4) = b^(2x-4),

Simply, x=2.

(2)

SuryaTeja said:
4 years ago

Am not getting this, please explain in detail.

(2)

Panther said:
6 years ago

How come 4?

(2)

Frazer Juma said:
5 years ago

Thanks, guys! I understood very well.

(1)

Ashish said:
6 years ago

I am not geting. How to solve this?

(1)

Sachin d said:
7 years ago

Thanks @Heman.

(1)

Husain SR said:
8 years ago

Here (a/b)^x-1 and (b/a)^x-3 now if we reciprocal b/a to a/b then there is negative sign on it.

(a/b)^-(x-3).

Let compare thier powers;

x - 1 = -(x - 3).

x - 1 = -x + 3

x + x = 1 + 3.

2x = 4

x = 2 is answer.

(a/b)^-(x-3).

Let compare thier powers;

x - 1 = -(x - 3).

x - 1 = -x + 3

x + x = 1 + 3.

2x = 4

x = 2 is answer.

(1)

Lawal Adetunji said:
7 years ago

I am not getting this. Please help me to understand better.

Yesubabu said:
3 years ago

@Urvashi.

You are absolutely right, Thanks for explaining.

You are absolutely right, Thanks for explaining.

Shweta said:
7 years ago

@Husain.

When you compare the power then , x-1=-x-3.

Then how you change the sign of ,x-1=x+3?

When you compare the power then , x-1=-x-3.

Then how you change the sign of ,x-1=x+3?

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