Question

a shop keeper number of books for rs 200 hw would have brought 10 more book of each book cost 20 less how much
book did he buy

Answer 1

let the shopkeeper bought x number of books for Rs.200 

price for each book = 200/x 

If he had bought 10 more books for the same amount each book would have cost Rs 20 less

it means 

the cost of each books is decreased by 20 if he had bought 10 more books 

I.e.

ATQ 

200/x - 200/x + 10 = 20 

200(1/x - 1/(x+10)   = 20 

1/x - 1/x+10              = 20/200 

(x+10) - x /x(x+10)    = 1/10

x+10 -x                     = x² + 10x / 10 

100                           = x² + 10x 

x² + 10x - 100           = 0 

Here quadratic equation formed ...

x² + 10x - 100           = 0 

No two such factors can be found !!