Question

If I multiply a number by 10 and subtract 9,

I get the square of the number.
What could the number be?

Answer 1

n = the number
10n - 9 = n2
0 = n2 - 10n + 9
0 = (n - 1)(n - 9)

{ 1, 9 }

The number could be either 1 or 9.

Answer 2

The two numbers which satisfy the given statement are 1 and 9

Explanation:

Given as :

A number is multiply by 10 and subtracted 9 , then square of number is formed :

So, Let The number be x

Or, ( 10 × x ) - 9 = x²

Or, 10 x - 9 = x²

Or, x² - 10 x + 9 = 0

Or, x² - x - 9 x + 9 = 0

Or, x ( x - 1 ) - 9 ( x - 1 ) = 0

so, ( x - 1 ) ( x - 9 ) = 0

∴ x = 1 and x = 9

Hence The two numbers which satisfy the given statement are 1 and 9 Answer