Question

The square of 9 less than a number is 3 less than the number. What is the number?

-12 or 7
-12 or -7
1-7 or 12
7 or 12

Answer 1

D. 7 or 12

Explanation:

Just took it. Edg 2020. Hope this helps :)

Answer 2

7, 12

Explanation:

( n-9)^2 = n-3

Foil the right

n^2 -18n +81 = n-3

Subtract n from each side

n^2 -19n +81 =-3

Add 3 to each side

n^2 -19n +84 = 0

Factor

What 2 numbers multiply to 84 and add to -19

-12*-7 = 84

-12+-7 = -19

( n-7) (n-12) =0

Using the zero product property

n-7 =0 n-12= 0

n=7 n=12