A rock is thrown upward with a velocity of 25 meters per second from the top of a 49 meter high cliff, and it misses the cliff on the way back down. When will the rock be 8 meters from ground level?

32

step-by-step explanation:

mk./km: lm

step-by-step explanation:

,mlmlm

; mk

lk

solution:

the given function is ,

      =

the three roots of this quadratic function is , 0 ,8 and 10.all the roots are real and rational.

if a quadratic equation is of the form ,

sum of the roots = a + b +c= 0+8+10=18=  

product of roots taken two at a time = a b + b c+ c a = 0+80+0=80 =  

product of roots = a b c = 0=  

there are 11 doors in a hall starting from 0 to 11.the entry in the hall is permitted through gate number 0 and exit is allowed through only gate number 8 and 10.so, three roots(0,8,10) of quadratic function is given by entry and exit route of this hall.

the answer is d

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