3 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]3 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

Need help asap!!!! will mark brainliest if correct

ehidna [41]

The volume of a rectangular prism is length x width x height.
You will have to multiply 10.4mm by 5mm by 8mm and the product of that is 416 mm

5 0

3 years ago

Read 2 more answers

the product of a number X and 6 is 4 more than the product of the number and 3/8 which answer represents the situation

mart [117]

6x=4+3/8x

That will be the answer

4 0

3 years ago

Which equation can you use to find the value of x?

klemol [59]

Answer:

$3x=78+(x-2)$

Step-by-step explanation:

The complete question in the attached figure

we know that

The <u><em>Triangle Exterior Angle Theorem</em></u> states that: An exterior angle of a triangle is equal to the sum of the opposite interior angles.

In this problem

$3x=78+(x-2)$

solve for x

$3x=76+x\\3x-x=76\\2x=76\\x=38^o$

3 0

3 years ago

Abigail's mom asked her to go to the store and purchase 5 kilograms (kg) of potatoes. When she got to the store, she saw the pot

Over [174]

1 kilogram = 2.205 pounds

5 kg * 2.205 lbs = 11.0231 pounds

Round to pounds = 11
Round to tenths/1 decimal = 11
Round to hundredths/2 decimals = 11.02

5 0

3 years ago

PLEASE ANSWER WILL GIVE BRAINLIEST IF CORRECT!!!

Airida [17]

Answer:

x = 118 units

Step-by-step explanation:

tan 50° = x/99

x = 99(tan 50°)

x = 117.9

5 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.