From AB = 0, r (a)+r (b) ≤ 3, ∴ r (b) ≤ 1, to "the third-order matrix b is not equal to 0" (the article in the title

)，∴R(B)≠0，r (b) = 1，？

3. The problem is not clear. ? Z- 1+？ The modulus of I = 1, namely | Z- 1+I | = 1 has been fixed. Why do you ask "Z- 1+? Me? about

Minimum value of the module ". You are asking, "What is the minimum value of the modulus z and the radial angle of the complex number z with the minimum value? "

If so, the minimum value of |Z| is √2- 1, and the radial angle of z is -∏/4? .

As shown in the figure. Z0 =-1+i.z1= a+bi = z-1+i. | z | = | z1-z0 | (blue line length).

|Z| The minimum value is the length of the red line segment, and z is the red vector. The minimum value of |Z| is √2- 1,

The radial angle of z is -∏/4? .