We have been given an expression [tex]2\sqrt{28} -5\sqrt{63}[/tex] and we are asked to find correct option from the given choices.
Let us simplify our expression.
[tex]2\sqrt{28} -5\sqrt{63}[/tex]
First of all we will take out perfect squares from our radical.
[tex]2\sqrt{7\cdot4} -5\sqrt{7\cdot9}[/tex]
[tex]2\sqrt{4} \cdot\sqrt{7} -5\sqrt{9} \cdot\sqrt{7}[/tex]
[tex]2\cdot2\sqrt{7} -5\cdot3\sqrt{7}[/tex]
[tex]4\sqrt{7} -15\sqrt{7}[/tex]
[tex]-11\sqrt{7}[/tex]
Our expression simplifies to [tex]-11\sqrt{7}[/tex], therefore, option C is the correct choice.
