4 - 2x^2 = 0

2x^2 = 4

x^2 = 4/2

x^2 = 2

x= √2

3 - 12x^2= 0

12x^2 = 3

x^2 = 3/12 = 1/4

x = √(1/4)

x = +- 1/2

7 = 28x^{2}

x^2 = 7/28

x^2 = 1/4

x= √(1/4)

x= + - 1/2

1/4 + x^{2} = 0

x= не имеет решения

x^{2} - 2/9 = 0

х ^2 = 2/9

x = √(2/9)

x= + - √2/3