Answer: 3
Step-by-step explanation:
[tex]\sqrt{x+8}=\sqrt{2x+5}\\\\(\sqrt{x+8})^2=(\sqrt{2x+5})^2\\\\x+8=2x+5\\\\8=x+5\\\\3=x\\\\\\Check:\\\sqrt{(3)+8}=\sqrt{2(3)+5}\\\\\sqrt{11}=\sqrt{11}\ \checkmark[/tex]