# A shopkeeper buys a number of books for Rs. 1200. If he had bought 10 more books for the same amount, each book would have cost Rs. 20 less. How many books did he buy?

Let x be the no. of books and y is the cost of each book.

––––––(1)

when 10 more students appear then,

––––(2)

On solving both (1) and (2) equation

subtracting (2) from (1)

600 = x2 + 10x

x2 + 10x – 600 = 0

On applying Sreedhracharya formula

X = – 30 or X = 20

The number of books, he purchased are 20. (as only positive values are considered).

Rate this question :

How useful is this solution?
We strive to provide quality solutions. Please rate us to serve you better.
Related Videos
Quiz | Knowing the Nature of Roots44 mins
Take a Dip Into Quadratic graphs32 mins
Foundation | Practice Important Questions for Foundation54 mins
Nature of Roots of Quadratic EquationsFREE Class
Getting Familiar with Nature of Roots of Quadratic Equations51 mins
Quadratic Equation: Previous Year NTSE Questions32 mins
Champ Quiz | Quadratic Equation33 mins
Champ Quiz | Quadratic Equation48 mins
Balance the Chemical Equations49 mins
Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Experts
Dedicated counsellor for each student
24X7 Doubt Resolution
Daily Report Card
Detailed Performance Evaluation
view all courses