Which choice is equivalent to the product below when [tex]$x \geq 0$[/tex]?

[tex]\sqrt{10 x^2} \cdot \sqrt{5 x}[/tex]

A. [tex]x \sqrt{15}[/tex]
B. [tex]5 x \sqrt{2}[/tex]
C. [tex]\sqrt{15 x^2}[/tex]
D. [tex]5 x \sqrt{2 x}[/tex]



Answer :

To find the equivalent expression for [tex]\(\sqrt{10 x^2} \cdot \sqrt{5 x}\)[/tex] when [tex]\(x \geq 0\)[/tex], we'll follow a step-by-step approach:

1. Simplify Each Square Root:
- [tex]\(\sqrt{10 x^2}\)[/tex]
- [tex]\(\sqrt{5 x}\)[/tex]

Let's handle them one at a time.

[tex]\[ \sqrt{10 x^2} = \sqrt{10} \cdot \sqrt{x^2} \][/tex]

Since [tex]\(\sqrt{x^2} = x\)[/tex] (because [tex]\(x \geq 0\)[/tex]), we have:

[tex]\[ \sqrt{10 x^2} = \sqrt{10} \cdot x \][/tex]

Next, consider:

[tex]\[ \sqrt{5 x} = \sqrt{5} \cdot \sqrt{x} \][/tex]

2. Multiply the Simplified Expressions:

We now multiply the two simplified expressions:

[tex]\[ \sqrt{10 x^2} \cdot \sqrt{5 x} = (\sqrt{10} \cdot x) \cdot (\sqrt{5} \cdot \sqrt{x}) \][/tex]

This can be rewritten as:

[tex]\[ \sqrt{10} \cdot x \cdot \sqrt{5} \cdot \sqrt{x} \][/tex]

We can combine the square root terms:

[tex]\[ \sqrt{10} \cdot \sqrt{5} \cdot x \cdot \sqrt{x} = \sqrt{10 \cdot 5} \cdot x \cdot \sqrt{x} \][/tex]

Simplify inside the square root:

[tex]\[ \sqrt{50} \cdot x \cdot \sqrt{x} \][/tex]

Notice that [tex]\(\sqrt{50}\)[/tex] can be further simplified:

[tex]\[ \sqrt{50} = \sqrt{25 \cdot 2} = \sqrt{25} \cdot \sqrt{2} = 5 \cdot \sqrt{2} \][/tex]

Substituting this back in, we get:

[tex]\[ 5 \cdot \sqrt{2} \cdot x \cdot \sqrt{x} \][/tex]

3. Combine [tex]\(x\)[/tex] Terms:

Combine the [tex]\(x\)[/tex] terms:

[tex]\[ 5 \cdot \sqrt{2} \cdot x \cdot \sqrt{x} = 5 x \cdot \sqrt{2} \cdot \sqrt{x} = 5 x \cdot \sqrt{2 x} \][/tex]

Thus,

[tex]\[ \sqrt{10 x^2} \cdot \sqrt{5 x} = 5 x \cdot \sqrt{2 x} \][/tex]

This matches choice D:

[tex]\[ \boxed{5 x \sqrt{2 x}} \][/tex]