2 years ago

The 8th and 20th terms of an arithmetic sequence are 20 and 56 respectively. What is the 1st term of the sequence.

Mathematics

1 answer:

Ostrovityanka [42]2 years ago

6 0

Answer:

Step-by-step explanation:

$a_n=a_1+d(n-1)\\\\a_8=a_1+d\cdot7\\\\a_{20}=a_1+d\cdot19\\\\a_{20}-a_8=a_1+19d-(a_1+7d)=12d\\\\56-20=2d\\\\12d=36\\\\d=3\\\\\\ a_1+3\cdot7=20\\\\a_1=20-21=-1$

You might be interested in

Mario's heart beats 72 times per minute. how many times does it beat in a year. answer in standard form correct to 2 significant

klemol [59]

You would do 60 seconds multiplied by 24 hours in a day which would be 1440 beats then you would multiply by the number of days in a year which is 365 then you would get the awnser of 525,600 beats per year.

7 0

3 years ago

Read 2 more answers

Which term describes this figure?

Effectus [21]

Answer:

its a angle

Step-by-step explanation:

7 0

3 years ago

s2008m [1.1K]

It will be $105 a month

5 0

3 years ago

Savannah planned to evenly disperse 400 chocolate chips among the x pans of brownies. Unfortunately, the last pan of brownies re

bonufazy [111]

400 - 32 which equals 368

4 0

3 years ago

GEOMETRY!! Will give brainliest

svetoff [14.1K]

Answer:

Step-by-step explanation:

(20x15)0.5

6 0

2 years ago

Read 2 more answers

The 8th and 20th terms of an arithmetic sequence are 20 and 56 respectively. ​What is the 1st term of the sequence.

The 8th and 20th terms of an arithmetic sequence are 20 and 56 respectively. What is the 1st term of the sequence.