2 years ago

Given the sum s20= 910 of an arithmetic sequence and A20 = 95, Find A1

Mathematics

1 answer:

Inessa05 [86]2 years ago

5 0

Step-by-step explanation:

Sn=n/2(2a+(n-1)d)

910=n/2{2a+(n-1)d}

1820=n{2a+(n-1)d}

1820=20{2a+(20-1)d}

1820=20{2a+19d}

91=2a+19d

An=a+(n-1)d

95=a+(20-1)d

95=a+19d

91=2a+19d

---------------

4=-a

a=-4

91=2a+19d

91=2(-4)+19d

91=-8+19d

91+8=19d

99=19d

d=99/19

A=-4

You might be interested in

find the third,fifth and seventeenth terms of the sequence described by each explicit formula f(n)=8+3(n-1) and how you got it

alexira [117]

Answer:

Step-by-step explanation:

plug in 3 , 5 and 17 for n

8 + 3(3 -1) = 8 + 6 = 14

8 + 3(5-1) = 8 + 12 = 20

8 + 3(17-1) = 8 + 48 = 56

3 0

2 years ago

What is the answer to 30=-(7-x)?

Lemur [1.5K]

Step-by-step explanation:

$x = \frac{30}{7}$

6 0

2 years ago

Read 2 more answers

If the dimensions of a figure are doubled, how many times larger will the volume be?

dsp73

Answer:

2 Answers By Expert Tutors

Consider as an example a box of length L, width W, and height H. If all linear dimension are doubled the area becomes 4 (22) times the original

Step-by-step explanation:

google

3 0

2 years ago

PLEASEE 7TH GRADE MATH

Andrews [41]

Answer:

so first question is b)8/5p=c, explanation in comments and your second question is 25%explanation in comments!! Have a good day and hope this helped!!

Step-by-step explanation:

7 0

2 years ago

Cliff borrows $10 from his brother. The next day, he borrows another $15 from his brother. What integer represents the balance t

Ymorist [56]

Answer:

The answer is (0)15

Step-by-step explanation:

The ratio of the integer is stated to be as (0)15.

4 0

2 years ago

Given the sum s20= 910 of an arithmetic sequence and A20 = 95, Find A1​

Given the sum s20= 910 of an arithmetic sequence and A20 = 95, Find A1