Answer:
[tex] 19\sqrt{7} [/tex]
Step-by-step explanation:
[tex] 25\sqrt{7} - 2\sqrt{63} = [/tex]
[tex] = 25\sqrt{7} - 2\sqrt{9 \times 7} [/tex]
[tex] = 25\sqrt{7} - 2\sqrt{9} \sqrt{7} [/tex]
[tex] = 25\sqrt{7} - 2\times 3 \sqrt{7} [/tex]
[tex] = 25\sqrt{7} - 6 \sqrt{7} [/tex]
[tex] = 19\sqrt{7} [/tex]
