Aptitude - Problems on Numbers - Discussion
Discussion Forum : Problems on Numbers - General Questions (Q.No. 14)
14.
The sum of two number is 25 and their difference is 13. Find their product.
Answer: Option
Explanation:
Let the numbers be x and y.
Then, x + y = 25 and x - y = 13.
4xy = (x + y)2 - (x- y)2
= (25)2 - (13)2
= (625 - 169)
= 456
xy = 114.
Discussion:
30 comments Page 2 of 3.
Mahesh said:
1 decade ago
x+y=25.......1.
x-y=13.......2.
Add 1&2
2x = 38,
x = 19 (now substitute x val in 1).
19+y = 25.
y = 6.
x*y = 19*6.
= 114.
x-y=13.......2.
Add 1&2
2x = 38,
x = 19 (now substitute x val in 1).
19+y = 25.
y = 6.
x*y = 19*6.
= 114.
Kowselya said:
1 decade ago
4xy is the right way. But,easy way is,
Sum of two numbers->x+y = 25..........1.
Difference of same two numbers->x-y = 13......2.
1&2 solve, 2x = 38.
x = 19.
Sub the value x in equation 1,
The value of y is 6.
Finally, the product of two numbers, x*y = 19*6 = 114.
Sum of two numbers->x+y = 25..........1.
Difference of same two numbers->x-y = 13......2.
1&2 solve, 2x = 38.
x = 19.
Sub the value x in equation 1,
The value of y is 6.
Finally, the product of two numbers, x*y = 19*6 = 114.
(1)
Deepakamal said:
1 decade ago
x+y = 25 and
x-y = 13.
To solve this we can get x=19 and y=6.
But the question is product of two no.
So, xy = 19x6 = 114 is the answer
x-y = 13.
To solve this we can get x=19 and y=6.
But the question is product of two no.
So, xy = 19x6 = 114 is the answer
Hitesh said:
1 decade ago
Why taken 4xy?
JAYESH BRO, said:
1 decade ago
How 4xy?
Ans: Because there two number is 25 & for that's 2+.
(X+Y-X-Y=2xy).
That's why 2+2xy=4xy.
Ans: Because there two number is 25 & for that's 2+.
(X+Y-X-Y=2xy).
That's why 2+2xy=4xy.
Charles said:
1 decade ago
Thanks guys.
Tanishqa said:
9 years ago
How to substitute the value of x and y?
Kakali tripathi said:
9 years ago
Thanks @Prashanth.
Devendra said:
9 years ago
I am a primary school student, I have a doubt, anyone please clarify this. How to solve this question without taking the unknown variable X & Y?
Lav said:
9 years ago
x + y = 25.
x - y = 13.
2x = 12.
x = 6.
y = 19.
xy = 114.
x - y = 13.
2x = 12.
x = 6.
y = 19.
xy = 114.
(4)
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