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 3 of 3.
Subi said:
1 decade ago
X+y=25,
X-y=13.
Then add both equation, we get 2x=38 (+y-Y=1), Hence X=38/2 = 19.
So X=19,
19+y=25.
y=25-19=>6.
So product of XY = 19*6 = 114.
X-y=13.
Then add both equation, we get 2x=38 (+y-Y=1), Hence X=38/2 = 19.
So X=19,
19+y=25.
y=25-19=>6.
So product of XY = 19*6 = 114.
Lucky said:
1 decade ago
Another easy way is:
x+y=25.......1
x-y=13........2
Solving it we get x=19.
Substituting x=19 in 1st equation,
We get y=6.
Product= xy =19*6=114.
x+y=25.......1
x-y=13........2
Solving it we get x=19.
Substituting x=19 in 1st equation,
We get y=6.
Product= xy =19*6=114.
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)
ManiKumar said:
1 decade ago
Every One Just follows Prashanth one.
MANJUNATHYADAV said:
1 decade ago
HOW 4XY HAS COME?
Vaishu said:
1 decade ago
How 4xy?
Manikandan said:
1 decade ago
hi Prashanth it is good....
Prashanth said:
1 decade ago
x+y=25.......1
x-y=13........2
solving it we get x=19
substituting x=19 in 1st equation
we get y=6
product= xy =19*6=114
x-y=13........2
solving it we get x=19
substituting x=19 in 1st equation
we get y=6
product= xy =19*6=114
Veena said:
1 decade ago
How 4xy?
SHYAM said:
1 decade ago
Find the value of the variable X and Y separately and find the product of both.
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