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: \( 2 \sqrt{10 \cdot 2} = 2 \sqrt{20} = 4 \sqrt{5} \)