Question

Had neha scored 10 more marks in her mathematics test out of 50 marks, 9 times these marks would have been the square of her actual marks. how many marks did she get in the test?

Answer 1

Let the actual marks scored by Neha be x

Then, ATQ

9(x+10) = x²
9x+90 = x²
9x+90 -x² = 0
x²-9x-90 = 0 
x²+6x-15x-90 = 0
x(x+6)-15(x+6)=0
(x+6)(x-15)=0
x= -6,15

∴x=15      [neglecting negative value]

∴ Hence, the actual marks scored by Neha is 15.

Answer 2

let original marks of Neha be x

so , according to given condition ,

9× (x+10) = x^2

9x + 90 = x^2

x^2 - 9x - 90 = 0

x^2 - 15x + 9x - 90 = 0

x ( x - 15 ) + 9 ( x -15) = 0

( x - 15 ) ( x + 9 ) = 0

x - 15 = 0 or x + 9 = 0

x = 15 or x = -9

but x = -9 is not possible

so , x = 15