7x^2 - 4 = 0
7x^2 = 4
4
x^2 = ------ / : V
7
x = V4/7
x = - 2/V7 i x = 2V7
-----------------------------------------
проверим, верно ли
7 *(2V7)^2 - 4 = 0
4
7 *--------- - 4 = 0
7
верно
<span>t=корень из s - nv
t^2 = s - nv
nv = s - t^2
v = (s-t^2)/n
</span>