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 1 of 3.
Anu said:
1 decade ago
How is (i) and (ii) solved and we get answer as 4??
Anu said:
1 decade ago
2x=8; so x=4 ie.,(x+x)(-y+y) (3+5)
Caroline said:
1 decade ago
x - y = 3
x + y =5
---------------
2x =8
Therefore, x = 4.
x + y =5
---------------
2x =8
Therefore, x = 4.
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.
Samson said:
1 decade ago
x-y = 3
x+y = 5
________
2x = 8
________
2x/2 = 8/2.
x = 8/2.
i.e x = 4.
x+y = 5
________
2x = 8
________
2x/2 = 8/2.
x = 8/2.
i.e x = 4.
(1)
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.
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?
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?
Hani said:
9 years ago
Why 2x is equal to 8?
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.
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