Which set of ordered pairs contains only points that are on the graph y = 15 – 2x?
A {(-3, 18), (0, 15), (6, 9)}
B
{(-5, 10), (-3, 6), (5, -10)}
С
{(-5, 25), (-1, 17), (8, -1)}
D {(-7, 1), (-4, 7), (2, 19)}

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.