What are the values of a, b, and c in this equation?

x^2+4x-21=0

a = 1, b = 4, c = - 21
a = 1, b = 4, c = 21
a = 0, b = 4, c = - 21
a = 0, b = 4, c = 21

Astandard deck of cards contains 52 cards. one card is selected from the deck. (a) compute the probability of randomly selecting a seven or king. (b) compute the probability of randomly selecting a seven or king or jack. (c) compute the probability of randomly selecting a queen or spade.

Plzzzz i beg u asap ! what is the equation of this graphed line? enter your answer in slope-intercept form in the box.

Find the slope of the line passing through a pair of points