Answer: a=225
Step-by-step explanation:
[tex]a > 0\\\\x^2=a\\\\x^2-a=0\\\\(x-\sqrt{a} )(x+\sqrt{a}) =0\\\\\sqrt{a} -(-\sqrt{a} )=30\\\\2\sqrt{a} =30\\\\\sqrt{a} 15\\\\a=15^2\\\\a=225\\\\Proof:\\\sqrt{225} -(-\sqrt{225} )=2*\sqrt{225} =2*15=30\\\\[/tex]
