Two people enter the elevator in a 5-floor building. let and denote the floors that they want to go to. assume that and are independent and equtl to 2, 3, 4 and 5 with probabilities 1/4 ) write down the joint pmf

107.141592654

step-by-step explanation:

(a) x intercepts: -6 and 2

you can obtain these by solving the equation 0=x^2 +4x-12 using your favorite quadratic formula. but it is easy to verify -6 and 2 indeed satisfy this equation.

(b) y intercept: -12

this is obtained by setting x=0: 0^2+4*0-12 = -12

(c) the minimum value is: -16 (this is the vertex)

you can get the vertex by rewriting the equation into the form:

there is no global or local maximum as the function goes to infinity, so only in the limit sense: +infinity.

i'm pretty sure the second one is -4 and rational. the best way to solve is guess and check, or you may just know your multiplication facts really good.