Saved Bookmarks
| 1. |
`(sqrt15+sqrt35+sqrt21+5)/(sqrt3+2sqrt5+sqrt7)=?`A. `N + (1)/(N) = 7`B. `N^(2) + (1)/(N^(2)) = 5`C. `N^(3) + (1)/(N^(3)) = 9`D. `N^(4) + (1)/(N^(4)) = 23` |
|
Answer» Correct Answer - B::D `N=(sqrt(3)+sqrt(5)+sqrt(5)+sqrt7)/((sqrt(3)+sqrt(5))+(sqrt(5)+sqrt(7)))` `rArr (1)/(N) = (1)/(sqrt(5) + sqrt(7)) + (1)/(sqrt(5) + sqrt(3))` `= (1)/(2) (sqrt(7) - sqrt(3)), N = (sqrt(7) + sqrt(3))/(2)` `N + (1)/(N) = sqrt(7)` `N^(2) + (1)/(N^(2)) = (N + (1)/(N))^(2) -2 = 5` `(N^(4) + (1)/(N^(4))) = (N^(2) + (1)/(N^(2)))^(2) - 2 = 23` |
|