(x^2 - 25)^2 + (x^2 + 3x - 10)(x^2 + 3x - 10) = 0
( x^2 - 25)(x^2 - 25) + (x - 2)(x + 5)(x - 2)(x + 5) = 0
(x - 5)(x + 5)(x - 5)(x + 5) + (x - 2)^2(x + 5)^2 = 0
(x - 5)^2(x + 5)^2 + (x - 2)^2(x + 5)^2 = 0
(x + 5)^2( (x - 5)^2 + (x - 2)^2) = 0
( x + 5)^2( x^2 - 10x + 25 + x^2 - 4x + 4) = 0
( x + 5)^2( 2x^2 - 14x + 29 ) = 0
x + 5 = 0
x = - 5
2x^2 - 14x + 29 = 0
D = b^2 - 4ac = 196 - 232 = - 36 - отрицательный,значит,корней нет.
Ответ: уравнение имеет один корень: x = - 5.