Answer:
x = -1
x = 9
Step-by-step explanation:
First you have to equals the equation to zero, then you have to find two numbers that their sum equals 8 and multiplied equals -9. In this case, those numbers are -1 and 9.
[tex]x^2-8x=9\\x^2-8x-9=0\\(x+1)(x-9)=0\\[/tex]
After you find those numbers, you split the equation and equals each term to zero.
[tex](x+1)=0, x=-1\\(x-9)=0, x=9\\[/tex]
So the answer is x=-1 and x=9
Hope you understand!