AX = b
Aη1 = b
η2
.
ηt
also
Aλ1η1 = b
λ2η2
.
λtηt
=>
Aλ1η1-η1 = 0
λ2η2-η2
.
λtηt-ηt
=>
Aη1(λ1-1) = 0
η2(λ2-1)
.
ηt(λt-1)
=>
λ1+λ2+λ3...+λt= t