Question

If I subtract 20 from my number, then square the result, I get the same answer as if I square my number, then subtract 20 from the result
What is my number and how do you work it out?

Answer 1

The value of the unknown number is 10.5.

Let the unknown number = x

When 20 is subtracted from the number and the result is squared which is equal to the square of the unknown number minus 20:

(x - 20)² = x² - 20

expand the equation;

x² -  40x  +  400 = x²  - 20

collect similar terms together;

x² - x² - 40x = -20 - 400

-40x = -420

$x = \frac{420}{40}\\\\ x = 10.5$

Thus, the value of the unknown number is 10.5.

Learn more about word problem here: brainly.com/question/18336356