SOLUTION: A man is able to save #50.00 of his salary in a certain year and afterwards saves in any one year #20.00 more than he saved in the preceding year. How long does it take him to save
Algebra ->
Sequences-and-series
-> SOLUTION: A man is able to save #50.00 of his salary in a certain year and afterwards saves in any one year #20.00 more than he saved in the preceding year. How long does it take him to save
Log On
Question 1161224: A man is able to save #50.00 of his salary in a certain year and afterwards saves in any one year #20.00 more than he saved in the preceding year. How long does it take him to save #4370.00? Answer by Boreal(15235) (Show Source):
You can put this solution on YOUR website! sum=an=4370. This equals (n/2)(2a1+(n-1)d). a1=50 and d=20
so multiplying by 2, and 8740=n(100+20n-20)
100n+20n^2-20n=8740
20n^2+80n-8740=0
n^2+4n-437=0
n=-4+/-sqrt(1764)/2
=(1/2)(-4+42), positive root only
=19 years ANSWER
divide everything by 10
5/7/9/11/13/15/17/19/21/23/25/27/29/31/33/35/37/39/41=437
