Y^2-9^2
(y-9)(y+9)
To see if its right:
y*y+y*9-9*y-9*9
y^2+9y-9y-81
y^2-9^2
Solution :
It is given that four different prizes were awarded. So,
a). 4 ways for person 47 to win a prize
99 ways to give out the 2nd prize
98 ways to give the 3rd prize
97 ways to give the last prize
∴ P(99,3) = 99 x 98 x 97
b). 1 way to give person 47 their prize
1 way to give person 19 their prize
98 ways to give out the 3rd prize
97 ways to give out the last prize
So, P(98,2) = 98 x 97
So you divide 50 by 2 so there are 25 before him
The correct answer would be 8x12y3
