When $x = 2$ , which expression can be completely simplified to $4 \sqrt{5}$ ?
A. $2 \sqrt{5 x}$
B. $2 \sqrt{10 x}$
C. $5 \sqrt{2 x}$
D. $8 \sqrt{5 x}$

Answer

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Answer

B: $2 \sqrt{10 \cdot 2} = 2 \sqrt{20} = 4 \sqrt{5}$

Steps

Step 1 ：Substitute $x = 2$ into each expression

Step 2 ：A: $2 \sqrt{5 \cdot 2} = 2 \sqrt{10}$

Step 3 ：B: $2 \sqrt{10 \cdot 2} = 2 \sqrt{20} = 4 \sqrt{5}$