Aptitude - Surds and Indices - Discussion
Discussion Forum : Surds and Indices - General Questions (Q.No. 4)
4.
If 5a = 3125, then the value of 5(a - 3) is:
Answer: Option
Explanation:
5a = 3125 
5a = 55
a = 5.
5(a - 3) = 5(5 - 3) = 52 = 25.
Discussion:
18 comments Page 1 of 2.
Urvashi said:
5 years ago
Given that 5^a = 3125
5^a = (5*5*5*5*5)
Since (5*5*5*5*5) = 3125.
So, 5 power a = 5 power 5.
Since bases are same!
Then subtract 3 from each according to question!
5^(a-3) = 5^(5-3),
5^(a-3) = 5^2,
5^(a-3) = (5*5).
5^(a-3) = 25.
5^a = (5*5*5*5*5)
Since (5*5*5*5*5) = 3125.
So, 5 power a = 5 power 5.
Since bases are same!
Then subtract 3 from each according to question!
5^(a-3) = 5^(5-3),
5^(a-3) = 5^2,
5^(a-3) = (5*5).
5^(a-3) = 25.
(3)
Muhammad shahid said:
1 year ago
As we know;
5^a = 3125.
3125 = 5^5.
5^a = 5^5.
So. comparing power
a = 5
5^(a-3)
put a = 5
5^(5-3)
5^2 = 25
So, 25 is the correct answer.
5^a = 3125.
3125 = 5^5.
5^a = 5^5.
So. comparing power
a = 5
5^(a-3)
put a = 5
5^(5-3)
5^2 = 25
So, 25 is the correct answer.
Ayesha said:
8 years ago
Why in the question they have to ask 5a they should have directly written it as 5^a did they get the same meaning?
Please, someone tell me.
Please, someone tell me.
Aditya said:
8 years ago
5a=3125 we can write 3125 in 5 * 5 * 5 * 5 * 5 then we get 5 power 5 then put value.
Then, we get 5 power 2 we get 25.
Then, we get 5 power 2 we get 25.
Bisu said:
1 decade ago
Also can be solved.
5^a = 3125.
5^(a-3) = ?
==>5^(a-3) = 5^a/5^3 = 3125/125 = 25.
5^a = 3125.
5^(a-3) = ?
==>5^(a-3) = 5^a/5^3 = 3125/125 = 25.
Siddharth sahu said:
4 years ago
The simple method is 5^a/5^3 = 3125/5^3.
That is equal to 5^a-3=3125/125 = 25.
That is equal to 5^a-3=3125/125 = 25.
(4)
Shalini said:
8 years ago
@Veronika:
^ means raise to the power, i.e. 5^a= 5 raise to the power a.
^ means raise to the power, i.e. 5^a= 5 raise to the power a.
Veronika said:
9 years ago
I am very new to this, what does ^ mean?
I really need help.
I really need help.
Asra said:
6 years ago
How to get the value of a by 5^a= 3125?
Someone please help.
Someone please help.
(1)
Swapnil said:
9 years ago
5 a-3 = 5^a/5^3.
= 3125/125.
= 25.
= 3125/125.
= 25.
(1)
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