Answers are
a: 4 square root 5
b: 16
c: 6
d: 8 square root 5

Step-by-step explanation:

Look at the picture.

ΔABC and ΔADB are similar. The corresponding angles are in proportion:

We have:

Substitute:

                cross multiply

        use √ab = √a · √b

since your problem is x^4 = 81, what you have to undeo is the "to the fourth power" part.

the inverse (opposite operation) of "to the fourth power" is "to the fourth root".

  (x^4) ^ ¼   = 81 ^ ¼  

  81 = 3^4     so (3 ^ 4) ^ ¼   =   3 ^ 1   = 3

by hand: (3 ^ 4) ^ ¼   =   3 ^ (4 x ¼) = 3 ^ 1   = 3   (when you take a power to a power, multiply the exponents.)

or, do it by calculator. one way of finding the fourth root is to use ^ (1/4)

step-by-step explanation:

i dont know sorry

step-by-step explanation: