Question

9 times a certain whole number is equal to 5 less than twice the square of the number find the number​

Answer 1

Let the unknown number be 'x'

9 times x is equal to 5 less than twice x²

Writing this down as an equation, we get

$9x = 2x^2-5$

$2x^2-9x-5 = 0$

$2x^2+x-10x-5 = 0$

$x(2x+1)-5(2x+1) = 0$

$(x-5)(2x+1) = 0$

x = 5  OR  x = -1/2

Since it is given that x is a whole number, we reject -1/2

So, the answer is

$\huge\black\boxed{x=5}$

Verification:

9 times 5 = 45

5 less than twice the square of 5 = 2×5² - 5 = 50 - 5 = 45

So the answer has been verified to be 5 itself.

HOPE THIS HELPS!!