value of sin e^x  is lie b/w -1 to 1

means -1<=sin e^x <=1

and for r.h.s  apply A.M>=G.M

5^x + 5^-x/2^.>=(5^x * 5^-x)^1/2=1

^.5^x + 5^-x>=2

so r.h.s is always greater than 2 and l.h.s is always less than or equal to 2

so there is no. solution

(2)x ^4+y(power4)=3789108

sorry my time has out. i will post ur ans at night.