Question

Four times of a positive whole number is 30 less than twice thecsquare of the number.The number is:

Answer 1

let the number be x
then the required statement will be

4x+30 = 2x²
2x² - 4x - 30 = 0
2x² -10x + 6x -30 = 0
2x( x-5 ) + 6( x-5 )=0
(2x+6)(x-5) =0

2x+6=0
x= - 6/2


x-5=0
x=5