Answer:
[tex]-11\sqrt{7}[/tex]
Step-by-step explanation:
Given expression,
[tex]2\sqrt{28}-5\sqrt{63}[/tex]
[tex]=2\sqrt{7\times 4}-5\sqrt{7\times 9}[/tex] ( HCF(28, 63) = 7 )
[tex]=2\sqrt{7}\times \sqrt{4}-5\sqrt{7}\times \sqrt{9}[/tex]
[tex](\because \sqrt{a\times b}=\sqrt{a}\times \sqrt{b})[/tex]
[tex]=2\sqrt{7}\times 2-5\sqrt{7}\times 3[/tex]
[tex]=4\sqrt{7} - 15\sqrt{7}[/tex]
[tex]=(4-15)\sqrt{7}[/tex] (By taking √7 common from both terms)
[tex]=-11\sqrt{7}[/tex]
