Answer:
D = -6, E = -8 , F = 0
Step-by-step explanation:
standard form = 
now, when circle passes through (3,-1);
⇒ 
⇒
...............( equation 1)
when circle passes through (-2,4);
⇒ 
⇒
...............( equation 2)
when circle passes through (6,8);
⇒ 
⇒
................( equation 3)
by solving these 3 equations , we get;
D = -6, E = -8, F = 0
hence,
standard form = 
= 
X could be the positive integers 2, 3, 4, or 5
I think the answer is -7.8
<h3><u>Answer</u>:- </h3>

<h3><u>Solution:-</u></h3>
<u>Given </u><u>that </u><u>:</u><u>-</u>
- job last for h hours
- Cost of job lasting more than 1 hour = $30
- Cost for the first hour = $75
Remaining hours for which the job will last after first hour= (h-1)
<u>Therefore</u>,
Cost for subsequent hours = 30×(h-1)
= 30(h-1)
Total Cost for job = Cost for 1st hour + Cost for subsequent hours
