MathDB
IMO LongList 1987 - Complex and real numbers

Source:

September 6, 2010
trigonometrycomplex numbersalgebra unsolvedalgebra

Problem Statement

It is given that a11,a22a_{11}, a_{22} are real numbers, that x1,x2,a12,b1,b2x_1, x_2, a_{12}, b_1, b_2 are complex numbers, and that a11a22=a12a12a_{11}a_{22}=a_{12}\overline{a_{12}} (Where a12\overline{a_{12}} is he conjugate of a12a_{12}). We consider the following system in x1,x2x_1, x_2: x1(a11x1+a12x2)=b1,\overline{x_1}(a_{11}x_1 + a_{12}x_2) = b_1,x2(a12x1+a22x2)=b2.\overline{x_2}(a_{12}x_1 + a_{22}x_2) = b_2. (a) Give one condition to make the system consistent.
(b) Give one condition to make argx1argx2=98.\arg x_1 - \arg x_2 = 98^{\circ}.