Question

the sum of the reciprocal of Sir Issac Newton age's (in years), 3 years ago and 5 years from how is 1/3.Find his present age.​

Answer 1

Answer:

7

Step-by-step explanation:

let Newton`s present age be 'a'

his age 3 years ago= a-3

age five years from now=a+5

Now sum of their reciprocals=1/3(given)

=>1/a-3 + 1/a+5=1/3

=>a+5+a-3/(a-3)(a+5)=1/3

=>2a+2/a^2+5a-3a-15=1/3

=>2a+2=1/3(a^2+2a-15)

=>6a+6-a^2-2a+15=0

=>-a^2+4a+21=0

=>a^2-4a-21=0

by factorisation,

=>a^2-(7-3)a-21=0

=>a^2-7a+3a-21=0

=>a(a-7) + 3(a-7)=0

=>(a-7)+(a+3)=0

therefore,a=7 or a=-3(not possible

as age can't be

negative)

therefore present age =7