Twenty one times of a positive number is less than its square by 100 The value of the positive numbe...........

Quantitative Aptitude (CGL) Number System

Twenty one times of a positive number is less than its square by 100. The value of the positive number is

let number is x
21x=x^2-100
x^2-21x-100=0
x(x-25)+4(x-25)=0
x=25 or x=-4
but no is positive
therefore x=25

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