# 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

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.

 Vijay said: (Jan 21, 2022) Yes, A^m * A^n = A^m+n.

 Glory said: (May 14, 2022) Thanks everyone.