tim did 10 lunges on day 1 and continued this doing 4 more lunges on each day.on day 7th he took a break and did nt do any day day.what is the equation for this? express it in the form y=ax(x+b)+c, where a,b and c are constants.x= no of days and y=no of lunges tim did

I don't believe the x in ax belongs there. So, instead of y = ax(x + b) + c, it should be y = a(x + b) + c

Now, this is an Arithmetic Progression (A.P.) with the following formula: , where:
                                                                           is the value of the nth term                                                                           
                                                                           is the 1st term (10, in this case)
                                                                           is the term number
                                                                           is he common difference (4, in this case)
                                                             
In the form y = a(x + b) + c,  translates to y = 4(x - 1) + 10, with a, b, and c being constants
4, - 1, and 10, respectively. With him taking a break on day 7, he only did lunges for 6 days, so x would range from 1 - 6.

I'm TOTALLY CONFUSED as to what the other person did. His/her equation seems EXTREMELY weird!!!

Domain is integers 1 through 6.

DAY COUNT,x       LUNGES, y
  1                 10
  2                 10+4(2-1)
  3                 10+4(3-1)
  4                 10+4(4-1)
  5                 10+4(5-1)
  6                 10+4(6-1)