Question

A shopkeeper buys a number of books rupees 800. If he had bought 4 more books for the same amount is book would have cost him rupees 10 less . How many books did you buy?

Answer 1

Let the number of books purchased for ₹ 800 be x


Then , cost of each book= ₹ 800/x……..(1)


If he buys 4 more books, then number of books= x+4


Cost of each book= ₹ 800/(x+4)..........(2)


A.T.Q


800/x - 800/(x+4)= 10


(800x+ 3200-800x)/x(x+4)= 10


3200= 10x(x+4)


3200= 10x²+40x


10x²+40x=3200


10x²+40x-3200=0


10( x²+4x-320)=0


x²+4x-320=0


x²+20x-16x-320=0


x(x+20)-16(x+20)=0


(x+20) (x-16)=0


x+20=0   or   x-16=0


x= -20    or    x= 16


[Numbers of books cannot be negative]


Neglecting x=-20, we get x=16


Hence, number of books purchased =16


HOPE THIS WILL HELP YOU.....

Answer 2

Answer:Let the number of books purchased for ₹ 800 be x

Then , cost of each book= ₹ 800/x……..(1)

If he buys 4 more books, then number of books= x+4

Cost of each book= ₹ 800/(x+4)..........(2)

A.T.Q

800/x - 800/(x+4)= 10

(800x+ 3200-800x)/x(x+4)= 10

3200= 10x(x+4)

3200= 10x²+40x

10x²+40x=3200

10x²+40x-3200=0

10( x²+4x-320)=0

x²+4x-320=0

x²+20x-16x-320=0

x(x+20)-16(x+20)=0

(x+20) (x-16)=0

x+20=0   or   x-16=0

x= -20    or    x= 16

[Numbers of books cannot be negative]

Neglecting x=-20, we get x=16

Hence, number of books purchased =16

HOPE THIS help u....