What is the 41st term of the arithmetic sequence a1=17 and a15=-39? answers to pick. is the answer -143??

a) x=-147
b) x=-143
c) x=-139
d) x=-135

Question

What is the 41st term of the arithmetic sequence a1=17 and a15=-39? answers to pick. is the answer -143??

a) x=-147
b) x=-143
c) x=-139
d) x=-135

amistre64 · Answer

do you recall the formula for the sum of an arith seq?

anonymous · Answer

no im just doing makeup work i missed the notes for that day im just rushing trying to get done

amistre64 · Answer

it should be somewhere in your study material ....

anonymous · Answer

okay could you give to me so i could write down for my records

amistre64 · Answer

$$a_n=a_1+d(n-1)~:~n=1,2,3,...$$

anonymous · Answer

thank you is there any way you could guide me through the problem?

amistre64 · Answer

use a1 and a15 to find "d"

once you know the what d is you replace a15 by a41

anonymous · Answer

okayy

anonymous · Answer

for the answer i got -143 is that correct?

anonymous · Answer

@amistre64

anonymous · Answer

@hartnn

amistre64 · Answer

a1=17 and a15=-39

-39 = 17 + d(15-1)

(-39 -17)/14 =  d

a41 = 17 + (-39 -17)(40)/14

... i get -143 as well

anonymous · Answer

is -143 the answer ? @amistre64