Six hundred three thousand four hundred seventy-eight
Answer:
The correct answer is b.)
Step-by-step explanation:
Given:
Sequence -7, -4, -1, 2, 5....... => a₁ = -7, a₂ = -4, a₃ = -1, a₄ = 2 and a₅ = 5
We conclude that this sequence is arithmetic series.
First we must find difference d:
d = a₂ - a₁ = a₃ - a₂ = -4 - (-7) = -1 - (-4) = -4 + 7 = -1 + 4 = 3
d = 3
The formula for n-th term of the arithmetic series is:
aₙ = a₁ + (n-1) d
aₙ = -7 + (n-1) 3
God with you!!!
Answer:
the common ratio is either 2 or -2.
the sum of the first 7 terms is then either 765 or 255
Step-by-step explanation:
a geometric sequence or series of progression (these are the most common names for the same thing) means that every new term of the sequence is created by multiplying the previous term by a constant factor which is called the common ratio.
so,
a1
a2 = a1×f
a3 = a2×f = a1×f²
a4 = a3×f = a1×f³
the problem description here tells us
a3 = 4×a1
and from above we know a3 = a1×f².
so, f² = 4
and therefore the common ratio = f = 2 or -2 (we need to keep that in mind).
again, the problem description tells us
a2 + a4 = 30
a1×f + a1×f³ = 30
for f = 2
a1×2 + a1×2³ = 30
2a1 + 8a1 = 30
10a1 = 30
a1 = 3
for f = -2
a1×-2 + a1×(-2)³ = 30
-10a1 = 30
a1 = -3
the sum of the first n terms of a geometric sequence is
sn = a1×(1 - f^(n+1))/(1-f) for f <>1
so, for f = 2
s7 = 3×(1 - 2⁸)/(1-2) = 3×-255/-1 = 3×255 = 765
for f = -2
s7 = -3×(1 - (-2)⁸)/(1 - -2) = -3×(1-256)/3 = -3×-255/3 =
= -1×-255 = 255
Answer: I need help too
Step-by-step explanation:
I think is -6
Answer:
20 is the rate of change/slope
