Answer: [tex]-11\sqrt{7}[/tex]
Step-by-step explanation:
[tex]2\sqrt{28}-5\sqrt{63}[/tex]
= [tex]2\sqrt{4*7}-5\sqrt{7*9}[/tex]
= [tex]2*\sqrt{4}*\sqrt{7} - 5*\sqrt{7} *\sqrt{9}[/tex]
= [tex]2*2*\sqrt{7} - 5*\sqrt{7}*3[/tex]
= [tex]4\sqrt{7} - 15\sqrt{7}[/tex]
= [tex]-11\sqrt{7}[/tex]
