Aptitude - Surds and Indices - Discussion

Discussion :: Surds and Indices - General Questions (Q.No.1)

1. 

(17)3.5 x (17)? = 178

[A]. 2.29
[B]. 2.75
[C]. 4.25
[D]. 4.5

Answer: Option D

Explanation:

Let (17)3.5 x (17)x = 178.

Then, (17)3.5 + x = 178.

3.5 + x = 8

x = (8 - 3.5)

x = 4.5


Maneesha said: (Nov 29, 2010)  
4(power of 3.5)
17 to the power of x in the value is

Devika said: (Jan 20, 2011)  
How + came in second step?

Aravindhsvcoe said: (Aug 13, 2011)  
a^m+a^n=a^m+n.according this formula sum of LHS power is equal to RHS power.i.e.3.5+4.5 = 8.

Sid said: (Feb 25, 2012)  
(2^n * 6^ m+1 * 2^n+1 * 3^2m)/ (3^-n * 6^2m * 2^4+m)=181398528 then the value of n is?

Swati said: (Dec 16, 2013)  
Simple calculation is:

(17)3.5 x (17)x = (17)8.
So, 3.5+x = 8.

Means x = 8-3.5.
x = 4.5.

Ma Awa Barry said: (Feb 5, 2014)  
(17)3.5 x(17)x = (17)8.
Therefore,(17)3.5+x = (17)8.

x = (17)8-3.5.
x = (17)4.5.

Mithun said: (Jun 22, 2014)  
As per the laws of exponential (x)y.(x)m = (x)y+m.

(17)3.5*(17)x = (17)8.
3.5 + x = 8.
X = 8 - 3.5.
X = 4.5.

Taniya said: (Dec 21, 2014)  
@Mithun said the formula (x)y.(x)m = (x)y+m.

But in the second step when value are put then m is not write in the place after 17Ã-8 why?

David Wainaina said: (Jan 29, 2015)  
Simple maths you just do 8-3.5 = 4.5.

Krishnalal Reang said: (Aug 27, 2015)  
I want with explanation and simple solution.

Ayovin said: (Nov 14, 2016)  
Simple 8 - 3.5 = 4.5.

Y.Mamaki said: (Feb 18, 2017)  
=17^3.5 * 17^*=17^8.
=17^3.5* * =17^8.
=17*= 17^8-3.5.
=17*= 4.5.
Answer =4.5.

Rishikesh Agrawani said: (Jul 23, 2017)  
Just look at the below simple derivation.

a.a.a.......m times = a^m,
a.a.a.......n times. = a^n,
(a.a.a.......m times).(a.a.a.......n times) = a.a.a......m+n times = a^(m+n).

Now we got,
a^m . a^n = a^(m+n).
Applying the above formula to the given question,
17^3.5 . 17^x = 17^8,
17^(3.5+x) = 17^8,
3.5 + x = 8,
x = 4.5.

Harry said: (May 10, 2018)  
Please explain the calculation of 17^3.5.

Post your comments here:

Name *:

Email   : (optional)

» Your comments will be displayed only after manual approval.