(brainliest) please help i need it!!

4:   60x + 12

Step-by-step explanation:

The amount that she earns in a day is fixed, and already known, so no need to make a coefficient with that term. But, we dont know how much phones she would sell in one day, as that is not limited. Hence, making the variable the amount of phone's she sells, multiplied by 60, as she makes $60 per phone that she cells.

y= 60x+12

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.