The square of the difference between a number and 7 is 81 . Find the number(s).

Question

asked Dec 24, 2023 76.3k views

1 Answer

Tropin Alexey · Answer 1 · 2023-12-27T20:36:52+0000

Answer:

16 or -2

Explanation:

Let the number be x.

Difference between the number and 7

= x -7 or 7-x

The square of the difference between x and 7

= (x -7)²

(x -7)²= 81

Square root both sides:

$x - 7= \pm √(81)$

$x - 7 = \pm9$

Add 7 to both sides:

$x = 7\pm9$

x= 16 or x= -2

Thus, the number could either be 16 or -2.