1,(18)=1+0,(18)
0,(18)=x
18,(18)=100x
18+0,(18)=100x
18+x=100x
18=99x
x=18/99
x=2/11
0,(18)=2/11
1,(18)=1+0,(18) =1+2/11=13/11
2,(27)=7+0,(27)
0,(27)=x
27,(27)=100x
27+0,(27)=100x
27+x=100x
27=99x
x=27/99
x=3/11
0,(27)=3/11
1,(27)=1+0,(27) =1+3/11=14/11
0,(13)=x
13,(13)=100x
13+0,(13)=100x
13+x=100x
13=99x
x=13/99
0,(13)=13/99
2,(23)=7+0,(23)
0,(23)=x
23,(23)=100x
23+0,(23)=100x
23+x=100x
23=99x
x=23/99
x=23/99
0,(23)=23/99
2,(23)=2+0,(23) =2+23/99
2) x^2 + xy + ax + ay = x(x + y) + a(x + y) = (x + a)(x + y)
3) am - an + m - n = a(m - n) + 1(m - n) = (a + 1)(m - n)
4) 3x - 3y + ax - ay = 3(x - y) + a(x - y) = (3 + a)(x - y)
5) ab - a^2 + 2a - 2b = a(b - a) - 2(b - a) = (a - 2)(b - a)