1. The problem statement, all variables and given/known data It roughly translates to this: "Define linear dependency of vectors". I hope it makes any sense. "1, x, sinx; x is defined (-∞, +∞)." 2. Relevant equations 3. The attempt at a solution I believe that to solve this problem, I have to turn these vectors into a quadratic polynomial, something like this: "t^2+t+1". However I have no idea what substitution should I use in order to turn it into a polynomial. I checked the common trig substitutions and didn't find anything helpful.