...1. Find the values of x so that the tangent to the function y=3/(x^1/3) is parallel to the line x+16y+3=0?

find the derivative of y and set it equal to the slope of the given line, then solve for x.

2. Find the point on the parabola y=-x^2+3x+4 where the slope of the tangent is 5

find the derivative of y and set it equal to 5, then solve for x. don't forget that the question asks for a point on the original curve.