4b²+20b+25=0
Divide everything by 4
b²+5b+ 6.25=0
use the quadratic formula
x= (-b+ or - √b²-4ac) /2a
x= (-5 + or - √5²-4*1*6.25) /2(1)
x= -5/2 so
in this case, b= -5/2
A line is a set of points that has no beginning and no end.
The number of ways people can get off the elevator is 604800 ways.
In this question,
Number of people, n = 7
Number of floors, r = 10
The first person can leave elevator in one of 10 ways. Then second person has to choose from one of remaining 9 floors. Then third person in 8, fourth in 7 ways and so on.
Number of ways people can get off the elevator can be calculated as
⇒ 
⇒ 
⇒ 
⇒ 
⇒ 
⇒ 604800 ways.
Hence we can conclude that the number of ways people can get off the elevator is 604800 ways.
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Answer: let me check
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