# A girl is twice as old as her sister 5 yrs hence is the product of their age will be 160 find there present age

2
by 6tower

2014-11-07T20:44:51+05:30
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Comment has been deleted
• Brainly User
2014-11-07T21:29:29+05:30
Solution :
First of all , there is a mistake in your question , the question should be ..
A girl is twice as old as her sister 5 yrs hence  the product of their age will be 160 find their present age?               let Present age of Girl's Sister (in Years) = x
therefore , Girl's Present  age (in Years) = 2x
Five years later ,
Girls Sisters Age = x+5
Girls age = 2x+5
According to question ,
(x+5)(2x+5)=160
x(2x+5)+5(2x+5)=160
2x² + 5x +10x +25 =160
2x² +15x + 25 =160
2x² +15x + 25 -160 =0
2x² +15x  -135 =0
here a=2
b=15
c=-135
D=-b+√b²-4ac/2a
D= -15+√15² - 4 *2*(-135)/2*2
=-15+√225 +1080/4
=-15+√1305/4
=-15+36.12/4
= 21.12/4
=5.28

HENCE pRESENT AGE OF Girls Sister = 5.28 Years
and the Present Age of Girl = 2*5.28
=10.56 Years

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