Roll the dice twice in a row and get a and b respectively. What is the probability that f(x)=x*x-ax+b has two different zeros?

F(x)=x*x-ax+b has two different zeros, then there is.

a* a-4b & gt； 0

This combination is:

a=3，4，5，6 b= 1

a=3，4，5，6 b=2

a=4，5，6 b=3

a=5，6 b=4

a=5，6 b=5

a=5，6 b=6

Then a * * * has: 4+4+3+2+2 = 17 kinds.

There are 6*6=36 random numbers.

So the probability is: 17/36.