(x-4)^2+(x+7)^2=2x^2-1

x^2 - 8x + 16 + x^2 + 14x + 49 = 2x^2 - 1
2x^2 + 6x + 65 = 2x^2 - 1
2x^2 + 6x + 65 - 2x^2 + 1 = 0 
6x + 65 + 1 =  0
6x + 66 = 0 
6x = - 66
x = - 66/6
x = - 11 

Задание решено..............