Aptitude - Surds and Indices - Discussion
Discussion Forum : Surds and Indices - General Questions (Q.No. 5)
5.
If 3(x - y) = 27 and 3(x + y) = 243, then x is equal to:
Answer: Option
Explanation:
3x - y = 27 = 33 
x - y = 3 ....(i)
3x + y = 243 = 35 x + y = 5 ....(ii)
On solving (i) and (ii), we get x = 4.
Discussion:
21 comments Page 2 of 3.
Harsh said:
8 years ago
How to solve this? Please help me.
Otuboye said:
9 years ago
Please, can you explain clearly how to solve the y?
Anu said:
1 decade ago
How is (i) and (ii) solved and we get answer as 4??
Shahjahan said:
9 years ago
(x - y) + (x + y) = 3 + 5,
(x + x) - (y + y) = 8,
2x = 8,
x = 4.
(x + x) - (y + y) = 8,
2x = 8,
x = 4.
Hani said:
9 years ago
Why 2x is equal to 8?
Poonam vaidya said:
10 years ago
I can't got this answer.
Please anyone explain it in detail. Why we cut y?
Please anyone explain it in detail. Why we cut y?
Arjun said:
1 decade ago
How we can find the power?
Is there any short technique by which we can find easily?
Is there any short technique by which we can find easily?
Mohammed sani said:
1 decade ago
We used simultaneous equation in solving that, we find for x then y before we can get the final answer.
Anju said:
1 decade ago
3 (x-y) = 27.
x-y = 27/3.
x-y = 9 ----- (1).
3 (x+y) = 243.
x+y = 243/3.
x+y = 81 ----- (2).
(x+y) = 81.
(x-y) = 9.
-------------
2y = 72.
y = 72/2 = 36.
y = 36.
x-y = 9.
x-36 = 9.
x = 36/9.
x = 4.
x-y = 27/3.
x-y = 9 ----- (1).
3 (x+y) = 243.
x+y = 243/3.
x+y = 81 ----- (2).
(x+y) = 81.
(x-y) = 9.
-------------
2y = 72.
y = 72/2 = 36.
y = 36.
x-y = 9.
x-36 = 9.
x = 36/9.
x = 4.
Caroline said:
1 decade ago
x - y = 3
x + y =5
---------------
2x =8
Therefore, x = 4.
x + y =5
---------------
2x =8
Therefore, x = 4.
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