Using the distributive property of multiplication, we can simplify the expression as shown below:
[tex] \sqrt{7x} \sqrt{x}- \sqrt{7x}*7 \sqrt{7} \\ \\
= \sqrt{7} \sqrt{ x^{2} }-7 \sqrt{x} \sqrt{ 7^{2} } \\ \\
=x \sqrt{7} -7*7 \sqrt{x} \\ \\ \\
=x \sqrt{7} -49 \sqrt{x} [/tex]
