Which function has an inverse?
a)
f(x) = x2 + 3, x51
b)
f(x) = x2 + 8x - 9, x5-6
f(x) = 2x2 + 8x-4, xs-2
d)
f(x) = 2x2 - 4x + 1, x23

During the election for class president, 40% of the students voted for kellen, and 60% of the students voted for robbie. 500 students voted in total. how many more students voted for robbie than for kellen? answer with work : )