We are given the following expression:
![\sqrt[]{81x^2}](https://img.qammunity.org/2023/formulas/mathematics/college/11km0d6rwoqfv5pnmh1uai9ggdxox1lh4a.png)
To simplify this expression we will use the following property of radicals:
![\sqrt[]{ab}=\sqrt[]{a}\sqrt[]{b}](https://img.qammunity.org/2023/formulas/mathematics/college/36x8mrtqxls717blnt9mq87duprn6qlre4.png)
Applying the property we get:
![\sqrt[]{81x^2}=\sqrt[]{81}\sqrt[]{x^2}](https://img.qammunity.org/2023/formulas/mathematics/college/2r5dypfuho214pfxcugtq4ei9xrzg90aw3.png)
Now, the first radical is equal to 9 since 9 x 9 = 81, therefore, we get:
![\sqrt[]{81x^2}=\sqrt[]{81}\sqrt[]{x^2}=9\sqrt[]{x^2}](https://img.qammunity.org/2023/formulas/mathematics/college/vx27z0891o5gnd6pm4wowiiftgabnfel1o.png)
For the second radical we will use the following property of absolute values:
![\lvert x\rvert=\sqrt[]{x^2}](https://img.qammunity.org/2023/formulas/mathematics/college/8h6te9t0jud8zudgugnd98u02wo9lyhysa.png)
Replacing we get:
![\sqrt[]{81x^2}=\sqrt[]{81}\sqrt[]{x^2}=9\sqrt[]{x^2}=9\lvert x\rvert](https://img.qammunity.org/2023/formulas/mathematics/college/vgnon3qcxdang3hmptzslejsl7ssccwwx9.png)
Therefore, the expression reduces to the product of 9 and the absolute value of "x".