How would you solve for X in 36x^4+29x^2-7=0

36x^4+29x^2-7=0
(x^2+1)(36x^2-7) = 0
36x^2-7 = 0
x = ±sqrt(7)/6
or x^2 = -1
x = ±i
x = ±sqrt(7)/6 and ±i

36x^4 + 29x^2 - 7 = 0
36m^2 + 29m - 7 = 0 , m = x^2
36m^2 + 36m - 7m - 7 = 0
36m(m + 1) - 7(m + 1) = 0
(36m - 7)(m + 1) = 0

m = 7/36, -1
x^2 = 7/36, -1
x = (7^(1/2))/6, -(7^(1/2))/6, i, - i [where i and -i are non-real solutions and can be disregarded unless asked for in question]
x = (7^(1/2))/6, -(7^(1/2))/6