Question

can anyone explain this to me in a simple way please. if a third term of an arithmetic sequence is 14 and the 8th term is -1, find the values of a1 and d of the sequence

Answer 1

hey dude didnt u got it?????

Answer 2

not yet I will write my solution then you check where I got it wrong.

Answer 3

ok go on

Answer 4

i gave u the correct explanation in the last thread bro once check it and then do it again

Answer 5

a3=14, a8=-1
a3=a1+(n-1)d
14=a1+(3-1)d
a1=14-2d equation 1

Answer 6

yeah perfect

Answer 7

ok now equation 2
a8=a1+(n-1)d
-1=a1+(n-1)d
a1=-1+7d equation 2

Answer 8

and the second will
a1=-1-7d

Answer 9

Solving those two u will get a1=20 and d=-3

Answer 10

just a sec why is it -7 not 7 cause 8-1=7

Answer 11

arey yar +7 will be there when it is on left hand side and it will be negative when u transfer it to the other side

Answer 12

actual transfer in sesnse is that u will subtract it on both sides on the left hand side u will remain with zero and on rhs u will get that -ve sign

Answer 13

substitute same as u did in the first eqn
a1+(8-1)d=-1
a1+7d=-1
a1=-1-7d ok????

Answer 14

humm thanks that was my mistake I guess

Answer 15

hmmm k k

Answer 16

got d=-3

Answer 17

a1=8 am I correct

Answer 18

look at this I am trying to get the sequence but it does not work

Answer 19

a1 is 20 dude

Answer 20

yeah you are right sorry

Answer 21

sorry forgot to give you a medal