Question

A shop kesper byus number of books gor rs 80 if he had nought 4 more books for the same amount each book would have cost rs 1 less how many books did he buy

Answer 1

Answer:

let the number of books be x

total cost  rs 80

cost of each book 80/x

A/Q

[x+4][80/x-1] = 80

[x+4][80-x] = 80x

80x + 320 -x^2- 4x =80x

or x^2 +4x -320 =0

x^2 -20x + 16x -320 = 0

x[x - 20] + 16 [x-20] = 0

[x -20] [x+16] =0

now, x-20=0 ,x =20 and  x +16 =0 , x = -16

since number of books canot be -ve

therefore x = 20

hence number of books he did buy is 20

Step-by-step explanation:

Answer 2

$here \: is \: the \: answer$

GIVEN :::::::

PRICE OF X BOOKS IS RS80

TO FIND ::::::

NO. OF BOOKS HE BOUGHT

MATHEMATICAL APPLICATION USED :::::

QUADRATIC EQUATIONS

HOW TO FIND :::::::

GIVEN THAT NO. OF BOOKS BOUGHT IS X

BUYING X BOOKS COST HIM RS80

CASE 1

THEN, COST OF ONE BOOK = 80/X

CASE 2

NUMBER OF BOOKS = X + 4

COST OF ONE BOOK = 80/X+4

ACCORDING TO THE QUESTION,

80/X - 80/X+4 = 1

80(1/X - 1/X+4) = 1

80(4/X² + 4X) = 1

320/X² + 4X = 1

320 = X² + 4X

X² + 4X - 320 = 0

BY FACTORISING,

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

NO. OF BOOKS CANNOT BE ZERO.

HENCE,

NO. OF BOOKS = 16

COST OF ONE BOOK = 80/16 = Rs 5

PLEASE MARK AS THE BRAINLIEST...❤