These techniques for elimination are preferred for 3rd order systems and higher. They use "Row-Reduction" techniques/pivoting and many subtle math tricks to reduce a matrix to either a solvable form or perhaps provide an inverse of a matrix (A-1)of linear equation AX=b. Solving systems of linear equations (n>2) by elimination is a topic unto itself and is the preferred method. As the system of equations increases, the "condition" of a matrix becomes extremely important. Some of this may sound completely alien to you. Don't worry about these topics until Linear Algebra when systems of linear equations (Rank 'n') become larger than 2.
If we let m₁, m₂, and m₃ be the measures of the angles of the triangle, the equation that would relate them to each other is,
m₁ + m₂ + m₃ = 180
Given the measures of the first two angles, the measure of the third angle is calculated through the equation,
m₃ = 180 - (m₁ + m₂)
Substituting the known expressions,
m₃ = 180 - (-3x⁵ + 2x²)
Simplifying,
<em> m₃ = 180 + 3x⁵ - 2x²</em>
All of the surfaces are rectangular
I think this is the answer :)
