4. Vivek is 5 years older than Kishor. The sum of
the multiplicative inverses (reciprocals) of their
ages is 1. Find their present ages.
6
Answers
Answer:
Vivek is older than Kishor by 5 years. So, Vivek's age will be x + 5. But age cannot be negative so, age of Kishore is 10 years and that of Vivek is 10 + 5 = 15 years.
Step-by-step explanation:
Let the age of Kishore = x years
Vivek age = ( x + 5 ) years
according to the problem given ,
sum of reciprocals = 1/6
1/x + 1/( x + 5 ) = 1/6
( x + 5 + x )/[ ( x ( x + 5 ) ] = 1/6
6( 2x + 5 ) = x(x + 5 )
12x + 30 = x² + 5x
x² + 5x - 12x - 30 = 0
x² - 7x - 30 = 0
x² - 10x + 3x - 30 = 0
x( x - 10 ) + 3(x - 10 ) = 0
( x - 10 )( x + 3 ) = 0
Therefore ,
x - 10 = 0 or x + 3 = 0
x = 10 or x = -3
age should not be negative.
Therefore ,
age of Kishore = x = 10 years
age of Vivek = x + 5 = 10 + 5 = 15 years
I hope this helps you.
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