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miskamm [114]
3 years ago
11

What is the first term in a geometric sequence if the common ratio is −4 and the sum of the first four terms is −255?

Mathematics
1 answer:
posledela3 years ago
8 0
Sn=A1(1-r^n)/(1-r)
Sum of a finite geometric series formula
We know the sum, number of terms and rate, so you plug those in.
-255=A1(1-(-4)^4))/(1-(-4)
-255=A1(1-256)/5
-255=A1(-255)/5
-1275=A1(-255)
5=A1

Hope this helped! Let me know if you have any questions.
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In the arithmetic sequence {13, 6,-1,-8,...}, what is the common difference?
pav-90 [236]

════════ ∘◦❁◦∘ ════════

<h3>Answer = -7</h3>

════════════════════

<h3>Known</h3>

a = 13

U2 = 6

U3 = -1

U4 = -8

════════════════════

<h3>Question</h3>

d = ..?

════════════════════

<h3>Way to do </h3>

#since it gives a lot of number, i will just pick one of the nth term, ill choose U2

Un = a + (n-1)d

U2 = 13 + (2-1)d

6 = 13 + d

6 - 13 = d

d = -7

════════════════════

<h3>Note</h3>

• The formula of arithmetic sequence

<h2>Un = a + (n-1)d</h2>

n = nth term

a = first term

d = common difference

════════════════════

7 0
3 years ago
Who is correct and why?
Masja [62]

i believe the answer is the last one

3 0
3 years ago
Please help me in this one
ANEK [815]
The best choices are table 1.

All the input values are being multiplied by themselves by the output values.

This creates a congruent and linear correlation and congruence. 

I hope this helps!

Brainliest answer is always appreciated!
8 0
4 years ago
Using this diagram, find x and y
PilotLPTM [1.2K]

Answer:

x=13

y=11

Step-by-step explanation:

3y+5+52=90

3y=90-57

3y=33

y=33/3=11

4x=52

x=52/4=13

8 0
2 years ago
Read 2 more answers
Which is the graph of the linear equation y= -1/4 x + 3?
Lesechka [4]
We know that -1/4x means we have a negative slope, which excludes the 1st graph from our answer choices.
Second, we know that the y-intercept has to be 3, excluding the second and third graph.
This leaves us with the 4th graph as our answer
6 0
4 years ago
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