wait...that expression just took a while but radsimp is fast.

If you add 3 to z it takes longer...maybe hangs...but radsimp gives, quickly,

```
>>> radsimp(1/sqrt(sqrt(7)/7 + 2*sqrt(2) + 3*sqrt(3) + 5*sqrt(5))+3)
-1658283*sqrt(21)*sqrt(sqrt(7) + 14*sqrt(2) + 21*sqrt(3) + 35*sqrt(5))/260084635
 - 1507966*sqrt(14)*sqrt(sqrt(7) + 14*sqrt(2) + 21*sqrt(3) + 35*sqrt(5))/2600846
35 - 1141953*sqrt(sqrt(7) + 14*sqrt(2) + 21*sqrt(3) + 35*sqrt(5))/260084635 - 32
7012*sqrt(6)*sqrt(sqrt(7) + 14*sqrt(2) + 21*sqrt(3) + 35*sqrt(5))/260084635 + 13
46996*sqrt(10)*sqrt(sqrt(7) + 14*sqrt(2) + 21*sqrt(3) + 35*sqrt(5))/1300423175 +
 1278438*sqrt(15)*sqrt(sqrt(7) + 14*sqrt(2) + 21*sqrt(3) + 35*sqrt(5))/130042317
5 + 1577436*sqrt(210)*sqrt(sqrt(7) + 14*sqrt(2) + 21*sqrt(3) + 35*sqrt(5))/13004
23175 + 11654899*sqrt(35)*sqrt(sqrt(7) + 14*sqrt(2) + 21*sqrt(3) + 35*sqrt(5))/1
300423175 + 3
>>> _.as_numer_denom()
(-8291415*sqrt(21)*sqrt(sqrt(7) + 14*sqrt(2) + 21*sqrt(3) + 35*sqrt(5)) - 753983
0*sqrt(14)*sqrt(sqrt(7) + 14*sqrt(2) + 21*sqrt(3) + 35*sqrt(5)) - 5709765*sqrt(s
qrt(7) + 14*sqrt(2) + 21*sqrt(3) + 35*sqrt(5)) - 1635060*sqrt(6)*sqrt(sqrt(7) +
14*sqrt(2) + 21*sqrt(3) + 35*sqrt(5)) + 1346996*sqrt(10)*sqrt(sqrt(7) + 14*sqrt(
2) + 21*sqrt(3) + 35*sqrt(5)) + 1278438*sqrt(15)*sqrt(sqrt(7) + 14*sqrt(2) + 21*
sqrt(3) + 35*sqrt(5)) + 1577436*sqrt(210)*sqrt(sqrt(7) + 14*sqrt(2) + 21*sqrt(3)
 + 35*sqrt(5)) + 11654899*sqrt(35)*sqrt(sqrt(7) + 14*sqrt(2) + 21*sqrt(3) + 35*s
qrt(5)) + 3901269525, 1300423175)
```