Question

Help, i know the answer but i don’t know how to do the work

Answer 1

Answer:

C

Step-by-step explanation:

Using the rule of radicals

$\sqrt{a}$ × $\sqrt{b}$ ⇔ $\sqrt{ab}$

Simplifying each radical before combining them.

$\sqrt{45t}$

= $\sqrt{9(5t)}$

= $\sqrt{9}$ × $\sqrt{5t}$ = 3$\sqrt{5t}$

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$\sqrt{125t}$

= $\sqrt{25(5t)}$

= $\sqrt{25}$ × $\sqrt{5t}$ = 5$\sqrt{5t}$

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Hence

2(3$\sqrt{5t}$) - 3(5$\sqrt{5t}$

= 6$\sqrt{5t}$ - 15$\sqrt{5t}$

= - 9$\sqrt{5t}$ → C