A number which, when squared, gives a specified value (square root). Often has positive and negative values; the positive one is called the principal square root.
25の二乗根は5と-5だが、正の二乗根は5である。
The square roots of 25 are 5 and -5, but the positive square root is 5.
方程式x^2 = 9の二乗根はx = 3とx = -3だ。
The square roots of the equation x^2 = 9 are x = 3 and x = -3.
√16 = 4 は、16の正の二乗根を表す記号だ。
√16 = 4 denotes the positive square root of 16.