Solve the linear equation
for the following fields K {\displaystyle {}K} :
a) K = Q {\displaystyle {}K=\mathbb {Q} } ,
b) K = R {\displaystyle {}K=\mathbb {R} } ,
c) K = { 0 , 1 } {\displaystyle {}K=\{0,1\}} , the field with two elements from example,
d) K = { 0 , 1 , 2 , 3 , 4 , 5 , 6 } {\displaystyle {}K=\{0,1,2,3,4,5,6\}} , the field with seven elements from example.