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 1 of 3.
Anonymous said:
6 years ago
@All.
x+y=25.
x-y=13----->1
x= 13 + y.
So,
13 + y + y =25..
13 + 2y =25
2y=25 - 13
2y= 12
y=12/2
y=6.
x+6=25.
x=25 - 6
x=19.
xy=19*6=114.
x+y=25.
x-y=13----->1
x= 13 + y.
So,
13 + y + y =25..
13 + 2y =25
2y=25 - 13
2y= 12
y=12/2
y=6.
x+6=25.
x=25 - 6
x=19.
xy=19*6=114.
(28)
Papa said:
4 years ago
How 4xy? Please explain me.
(11)
Yoon Darli said:
7 years ago
x+y=25 -----------> 1.
x-y=13 ------------> 2.
-----------------------------
2x=38.
So, x=19,
When x=19, y=6(because x+y=25,y=25-x).
And then, xy=114.
x-y=13 ------------> 2.
-----------------------------
2x=38.
So, x=19,
When x=19, y=6(because x+y=25,y=25-x).
And then, xy=114.
(10)
Ugyen Jigme Chogyel said:
5 months ago
Let the two numbers be x and y.
The sum of two numbers is 25, which is:
x + y = 25 and, their difference is 13, which is:
x - y = 13.
So, when we subtract the sum and the difference we get;
x + y = 25,
-(x – y) = 13,
2y = 12,
y = 6.
Since, x + y = 25.
x + 6 = 25,
x = 25 - 6,
x = 19.
So, their product is x*y which is:
19 * 6 = 114(the answer).
Hope it helped.
The sum of two numbers is 25, which is:
x + y = 25 and, their difference is 13, which is:
x - y = 13.
So, when we subtract the sum and the difference we get;
x + y = 25,
-(x – y) = 13,
2y = 12,
y = 6.
Since, x + y = 25.
x + 6 = 25,
x = 25 - 6,
x = 19.
So, their product is x*y which is:
19 * 6 = 114(the answer).
Hope it helped.
(7)
Shashi said:
7 years ago
x+y=25 ---> (1)
x-y=13--> x=13+y ---> (2).
Now insert (2) in (1)
=13+y+y=25,
=13+2y=25,
=2y=25-13,
=2y=12,
::y=6.
Now take eq (1).
x+6=25,
x=19,
now x*y=19*6=114.
x-y=13--> x=13+y ---> (2).
Now insert (2) in (1)
=13+y+y=25,
=13+2y=25,
=2y=25-13,
=2y=12,
::y=6.
Now take eq (1).
x+6=25,
x=19,
now x*y=19*6=114.
(5)
Ezhili said:
2 years ago
4ab = (a+b)^2 - (a-b)^2.
4ab = 25^2 - 13^2.
= 625 - 169.
4ab = 456
ab = 456/4
= 114.
4ab = 25^2 - 13^2.
= 625 - 169.
4ab = 456
ab = 456/4
= 114.
(4)
Ganesh said:
8 years ago
Add 25+13=38
Sub. 25-13=12
Then we Wii take the ratio
38:12 which is
19:6
After multiple(19*6=114) these no. We will get 114.
Sub. 25-13=12
Then we Wii take the ratio
38:12 which is
19:6
After multiple(19*6=114) these no. We will get 114.
(4)
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)
Karthika said:
1 decade ago
(x+y)2 = x2 + y2 + 2xy -----------(1)
(x-y)2 = x2 + y2 - 2xy -----------(2)
Subtract (1) - (2) => (x+y)2 - (x-y)2 = 4xy...
(x-y)2 = x2 + y2 - 2xy -----------(2)
Subtract (1) - (2) => (x+y)2 - (x-y)2 = 4xy...
(1)
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)
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