Answer:
C
Step-by-step explanation:
Using the rule of radicals
[tex]\sqrt{a}[/tex] × [tex]\sqrt{b}[/tex] ⇔ [tex]\sqrt{ab}[/tex]
Simplifying each radical before combining them.
[tex]\sqrt{45t}[/tex]
= [tex]\sqrt{9(5t)}[/tex]
= [tex]\sqrt{9}[/tex] × [tex]\sqrt{5t}[/tex] = 3[tex]\sqrt{5t}[/tex]
-----------------------------------------------------------------------------
[tex]\sqrt{125t}[/tex]
= [tex]\sqrt{25(5t)}[/tex]
= [tex]\sqrt{25}[/tex] × [tex]\sqrt{5t}[/tex] = 5[tex]\sqrt{5t}[/tex]
---------------------------------------------------------------------------
Hence
2(3[tex]\sqrt{5t}[/tex]) - 3(5[tex]\sqrt{5t}[/tex]
= 6[tex]\sqrt{5t}[/tex] - 15[tex]\sqrt{5t}[/tex]
= - 9[tex]\sqrt{5t}[/tex] → C
