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
Yes it is linear since it's in the standard form Ax+By = C
A = 2
B = -8
C = 16
Answer:
A. 
Step-by-step explanation:
We want to find the Z-score of 
if the population mean is 
,and the population standard deviation is 
.
We use the formula:
We substitute the values to obtain:
The correct answer is A.
y=3x+38 is the expression for Sidney's weekly salary.
Step-by-step explanation:
Given,
Casey's weekly salary = x
Let,
y be the weekly salary of Sidney's.
According to given statement;
Sidney makes $38 more than 3 times Casey's weekly salary.
Sidney's weekly salary = 3 times Casey's weekly salary + $38
y=3x+38 is the expression for Sidney's weekly salary.
Keywords: variable, addition
Learn more about variables at:
#LearnwithBrainly
Answer:
Step-by-step explanation:
There are 50 hundreds in 5000.
No of defective bulb expected = 50 * 3 = 150
