If using the method of completing the square to solve the quadratic equation
x2 + 15x + 21 = 0, which number would have to be added to "complete the
square"?

I'm confused on this could anyone me and show me what i need to do to solve it.

Is there an x intercept in the equation 60*1.15^x

(03.03 mc) choose the graph below that correctly represents the equation 2x + 4y = 24. (5 points) select one: a. line through the points 0 comma 6 and 12 comma 0 b. line through the points 0 comma negative 6 and 12 comma 0 c. line through the points 0 comma negative 12 and 6 comma 0 d. line through the points 0 comma 12 and 6 comma 0