Q2. (8 pts, Solving Congruences) Let
a,b,d
, and
n>1
be arbitrary integers. 2.a. Prove that if
ad-=bd(modn)
, then
a-=b(mod(n)/(gcd(d,n)))
. 2.b. Solve
7x-=12(mod13)
for
xin{0,1,2,dots,12}
. 2.c. Solve
84x-38-=79(mod15)
for
xin{0,1,2,dots,14}
. 2.d. Solve
2x-=3(mod14)
for
xin{0,1,2,dots,13}
.