Answer:
The negative solution k = -1 is the desired solution.
Step-by-step explanation:
Let the given number = k
So, according to the question:
[tex]k^{2} - 9 = 8k[/tex]
or, [tex]k^{2} - 8k - 9 = 0[/tex]
Now, solving this quadratic equation, we get
[tex]\implies k^{2} - 9k + k - 9 = 0[/tex]
or, k ( k-9) + 1 (k-9) = 0
⇒( k-9)(k+1) = 0
or, ( k-9) = 0 , or (k+1) = 0
⇒ k = 9 or k = -1
Since we only want the negative solution , the k = -1 is the desired solution.