2x + 5(y - 1) when x=8 and y=5

16+24=40

Step-by-step explanation: 2x+5(y-1) when x=8 and y=5. put x where it belongs, by the 2 and do the same with y, by the -1. and then slove. 2*8= 16 , 5*5= 25-1, then add 16 and 24 together and get 40.

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.