<u>Answer:</u>
26. 
27. 
28. 
<u>Step-by-step explanation:</u>
26.
:
Taking square on both the sides to get:





For non-negative values for radical:


So solution for this: 
27. 
Subtracting 2 from both the sides to get:


Taking square root on both sides:




28. 
Adding
to both the sides to get:


Taking square on both sides:




Subtracting
from both sides to get:


Subtracting 4 from both sides:


Square both sides again:



and for non-negative radical 
therefore, solution is
.