X^4-35x^2-36=0
x^2 = t (t >= 0)
t^2 - 35t - 36 = 0
D = 35^2 - 4*1*(-36) = 1369 = 37^2
t12 = (35 +- 37)/2 = -1 36
t1 = -1 нет t >= 0
t2 = 36
x^2 = 36
x1 = 6
x2 = -6
ответ -6 и 6
