Question

Find 26th term in the arithmetic sequence: -15,-35,-55,-75,...

Answer 1

Answer:

Step-by-step explanation:

hello :

-75-(-55) = (-55)-(-35) = (-35)-(-15)=-20

the ratio diff is : d=-20

the nth term is :An=A1+(n-1)d      A1 =-15

An=-15+(n-1)(-20) = 15-20n+20

An = -20n+5

26th term when : n=26       A26 = -20(26)+5 = -515

A26= -515

Answer 2

Answer:

-515

Step-by-step explanation:

In this example the first value is −15 and every value afterwards is 20 less.

After substituting these values to above formula, we obtain:

All we have to do is add 25 twenties or 25 x 20 = 500 and -15 - 500 = -515