Does anyone know this?

9.4 m/s

Step-by-step explanation:

This is the concept of application of the Pythagorean theorem. The resultant speed of the motorboat which is crossing the river that has a northward current of 5 m/s at a speed of 8 m/s will be given by:

c^2=a^2+b^2

c^2=8^2+5^2

c^2=64+25

c^2=89

c=sqrt89

c=9.4 m/s

the answer to this question is in the pic

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.