Решите уравнение x²+2x-4=0

x^2 + 2x - 4 = 0 
D = 4  + 16 = 20
√D = 2√5
x1 = ( - 2 + 2√5)/2 = - 1 + √5
x2 = ( - 2 - 2√5)/2 = - 1 - √5