1) 4 quinta sqrt(3x+1)-8=0
2) cube root(5m+6)+15=2
1. I will assume you mean
4(fifthroot(3x+1) - 8 = 0
4(3x+1)^(1/5) = 8
(3x+1)^(1/5) = 2
raise both sides to the 5th power
3x+1 = 2^5
3x+1 = 32
3x = 31
x = 31/3
#2, same way
(5m+6)^(1/3) = -13
cube both sides
5m+6 = -2197
5m= -2203
m = -2203/5 or -440.6