Problems on Numbers
1. The sum of the 2 numbers is 13 and the sum of their squares is 85.
Find the numbers.
Solution:
Let
the numbers be x and (13-x).
x2+(13-x)2=85
[Given condition]
x2+169-26x+x2=85
2x2-26x+84=0
x2-13x+42=0
x2-7x-6x+42=0
x(x-7)-6(x-7)=0
(x-7)(x-6)=0
x=7,
6.
The
two numbers are 7 and 6.
2. If the sum of the two numbers is 22 and their product is 40. Find the difference between the 2 numbers.
Solution:
Let the numbers be x and y.
x+y = 22 and xy = 40 [Given]
(x-y)2= (x+y)2
– 4xy [Since (x+y)2 – 4xy = x2+2xy+y2-4xy = x2-2xy+y2]
= (22)2-4(40)
=484-160
(x-y)2= 324
x-y = 18
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