How can you find an integer ‘a’ such that ‘a’ is congruent to -11 (mod 21) and 90 <= a <= 110?
How does one prove that there exist integers a, b, and c so not all are zero and each has an absolute value of less than one million, such that |a + b (2^0.5) + c (3^0.5) | < 10 ^-11?