What is the value of dd in the equation root3 (k^d) = (root3 k)^53kd=(3k)5?

2 Answers

Given: root(3)(k^d)=(root(3)(k))^53kd=(3k)5

Cube both sides

k^d=(root(3)(k))^15kd=(3k)15

color(brown)("Doing it the 'hard way'")Doing it the 'hard way'

Write (root(3)(k))^15(3k)15 as

[ root(3)(k) xxroot(3)(k)xxroot(3)(k)] xx[ root(3)(k) xxroot(3)(k)xxroot(3)(k)] xx[ root(3)(k) xxroot(3)(k)xxroot(3)(k)] xx[ root(3)(k) xxroot(3)(k)xxroot(3)(k)]xx[ root(3)(k) xxroot(3)(k)xxroot(3)(k)][3k×3k×3k]×[3k×3k×3k]×[3k×3k×3k]×[3k×3k×3k]×[3k×3k×3k]

Which is the same as k^5 k5

Putting it all back together we have:

k^d=k^5kd=k5

Then by direct comparison we have:

d=5d=5
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

color(brown)("Doing it the more straight forward way")Doing it the more straight forward way

Write (root(3)(k))^15(3k)15 as k^((15/3)k(153)

but 15-:3 = 515÷3=5 giving

(root(3)(k))^15(3k)15 is the same as k^5k5

Then the rest is as above.

Aug 7, 2018

color(orange)(d = 5d=5

Explanation:

root3 k^d = (root 3 k)^53kd=(3k)5

k^(d/3) = (k^(1/3))^5kd3=(k13)5

k^(d/3) = k^(5/3)kd3=k53

d /cancel 3 = 5/cancel3

color(orange)(d = 5