Answer:
6
Step-by-step explanation:
Hello,
The two triangles are similar and x is positive, different from 0, so we can write.
[tex]\dfrac{x}{9}=\dfrac{12}{x}\\\\<=>x^2=12\times 9\\\\<=> x = \sqrt{4\times 3 \times 9}=2\times 3 \times \sqrt{3}\\\\<=> \boxed{\sf \bf x=6\sqrt{3} }[/tex]
Thanks
