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
Y = mx + b
slope(m) = 3/4
(5,-4)...x = 5 and y = -4
now we sub
-4 = 3/4(5) + b
-4 = 15/4 + b
-4 - 15/4 = b
-16/4 - 15/4 = b
- 31/4 = b....or - 7 3/4 = b
so ur equation is : y = 3/4x + (-31/4) or y = 3/4x - 31/4
Answer:
4.31 kilometer
..........................................
Answer:
2
Step-by-step explanation:
We get 0.811 as our depreciating value because we take 18.9% and turn it into a decimal. Then, we subtract that from 1. If we did 0.189 instead, it would depreciate at a rate of 81.1% annually.
Answer:
(6,2)
Step by Step explanation:
1- Add the two equations so the Xs cancel out
2- find y by dividing 6 from both sides
3- plug in the y value in the place of the y in one of the equations
4- solve the equation to find X
5 - put answer in correct format (x,y)
