Aptitude - Surds and Indices - Discussion
Discussion Forum : Surds and Indices - General Questions (Q.No. 9)
9.
(25)7.5 x (5)2.5 ÷ (125)1.5 = 5?
Answer: Option
Explanation:
Let (25)7.5 x (5)2.5 ÷ (125)1.5 = 5x.
| Then, | (52)7.5 x (5)2.5 | = 5x |
| (53)1.5 |
 |
5(2 x 7.5) x 52.5 | = 5x |
| 5(3 x 1.5) |
| |
515 x 52.5 | = 5x |
| 54.5 |
5x = 5(15 + 2.5 - 4.5)
5x = 513
x = 13.
Discussion:
8 comments Page 1 of 1.
Saptaparna Patra said:
5 years ago
Thanks for explaining the answer.
(2)
Bankerlang Khongtani said:
6 years ago
How come -4.5?
(1)
Praneel said:
8 years ago
515 x 52.5 = 5x,
54.5.
5x = 5(15 + 2.5 - 4.5),
5x = 513.
So, x = 13.
54.5.
5x = 5(15 + 2.5 - 4.5),
5x = 513.
So, x = 13.
(1)
Hma said:
9 years ago
By BODMAS, the division operation should be solved first.
Ashwath R said:
1 decade ago
Why can't I use log with base 5 here?
Bisu said:
1 decade ago
(25)^7.5 x (5)^2.5 / (125)^1.5 = 5^?
Using BODMAS Rule,
1st==> 125 = 5^3.
5^3*1.5 = 5^4.5.
So, 5^2.5/5^4.5 = 5^-2.
25 = 5^2.
5^2*7.5 = 5^15.0.
So,
5^15 * 5^-2 = 5^15-2 = 5^13.
Using BODMAS Rule,
1st==> 125 = 5^3.
5^3*1.5 = 5^4.5.
So, 5^2.5/5^4.5 = 5^-2.
25 = 5^2.
5^2*7.5 = 5^15.0.
So,
5^15 * 5^-2 = 5^15-2 = 5^13.
(2)
Yugank said:
1 decade ago
Can I solve L.H.S using BODMAS rule?
Ankit Mishra said:
1 decade ago
Some hint must be given for power.
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