Lösungen/Solutions/
B1S1Ue/Ex2

L = Lektion/ Leçon   -- Sprechstunde / heures de consultation
W = Work / Arbeit / Travail
A  =Anhang/  Annexe / Appendice

Ueb/Ex 1      L

Remove[a, b, c, d, e, f, g, h, i]

Solve[{
a + b + c == 
          s, 
d + e + f == 
          s, 
g + h + i == 
          s; 
a + d + g == 
          s, 
b + e + h == 
          s, 
c + f + i == 
          s, 
a + e + i == 
          s, 
c + e + g == 
          f, 
s == 100, h == 5, 
        i == 6
}, {a, b, c, d, e, f, g, h, 
        i}]

Solve[{
a + b + c == 
          s, 
d + e + f == 
          s, 
g + h + i == 
          s; 
a + d + g == 
          s, 
b + e + h == 
          s, 
c + f + i == 
          s, 
a + e + i == 
          s, 
c + e + g == f, 
        s == 100
}, {a, b, c, d, e, f, g, h, 
        i}]

Solve[{
a + b + c == 
          s, 
d + e + f == 
          s, 
g + h + i == 
          s; 
a + d + g == 
          s, 
b + e + h == 
          s, 
c + f + i == 
          s, 
a + e + i == 
          s, 
c + e + g == f, e == 20, 
        h == 6
}, {a, b, c, d, e, f, g, h, 
        i}]

Ueb/Ex 2      L

a = m^2 - n^2; b = 2  m n;  c = m^2 + n^2;
{a^2 + b^2, c^2} // Expand

a^2 + b^2 =!= c^2

Ueb/Ex 3      L

Sum[2 k + 1, {k, 0, n}]

Ueb/Ex 4      L

Sum[k, {k, 1, n}]