10 × -2 is -20
-20 -8 = -28
This is an arithmetic sequence because each term is 7 greater than the previous term, so 7 is what is called the common difference...
Any arithmetic sequence can be expressed as:
a(n)=a+d(n-1), a=first term, d=common difference, n=term number.
We know a=1 and d=7 so:
a(n)=1+7(n-1)
a(n)=1+7n-7
a(n)=7n-6
The above is the "rule" for the nth term.
1,680 divided by 400 = 4.2
So we know that Xian has done 4.2 laps.
4.2 divided by 14 = 0.3
0.3 x 100 = 30%
Therefore, Xian has finished 30% of the run
The only way the expression can be factored is if a -3 is pulled out...
-3(5t+2)
