public Vector2 Solve22(Vector2 b)
{
float a11 = Col1.x, a12 = Col2.x, a21 = Col1.y, a22 = Col2.y;
float det = a11 * a22 - a12 * a21;
Box2DXDebug.Assert(det != 0.0f);
det = 1.0f / det;
Vector2 x = new Vector2();
x.x = det * (a22 * b.x - a12 * b.y);
x.y = det * (a11 * b.y - a21 * b.x);
return x;
}