man repays a loan for rupees 3250 by paying rupees 20 the first month and then increases the payment Rupees 15 every month how long will it take him to clear up the loan
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Answer:
n=(-5+125)/6=120/6=20 months
Thus loan will get clear in 20months
Step-by-step explanation:
Let the loan get clear up in n months
The payments are as
20,20+15,20+15+15
This forms an AP with a=20 ,d=15,Sn=3250 and n=?
We know Sn=n/2 { 2a+(n-1)d}
3250=n/2 { 2*20+(n-1)*15 }
6500=n( 40+15n-15)
6500=25n+15n²
15n²+25n-6500=0
Diving by 5 we get
3n²+5n-1300=0
n={ -5 ±√(25+15600) }/2*3
={ -5±√(15625)}/6
={ -5±125)/6
Taking only +ve value
n=(-5+125)/6=120/6=20 months
Thus loan will get clear in 20months
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