I got the answer as letter C, can someone check me to make sure that is correct? Thank you in advance.

The x's cancel  so definitely is choice C:  1/9

Step-by-step explanation:

We have   root( 1/(x^2) )  *  root ((x^2) / 81)

simplifying this we get as follows:

root( 1/(x^2) )  *  root ((x^2) / 81)

=  *

=  ( 1/x )   *  (x/9)

the x's cancel

= 1/9

choice C   1/9

step-by-step explanation:

∆abc has the points a(1, 7), b(-2, 2), and c(4, 2) as its vertices. formed with the point d(1, 2) as its third vertex, then ∆abd is triangle.