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 t

Question

3 years ago

10

he result
What is my number and how do you work it out?

1 answer:

Natasha_Volkova [10] · Answer 1 · 2023-01-25T06:34:15+03:00

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

<em>expand the equation;</em>

x² - 40x + 400 = x² - 20

<em>collect similar terms together;</em>

x² - x² - 40x = -20 - 400

-40x = -420

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

Thus, the value of the unknown number is 10.5.

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