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
Area of triangle = 1/2 (6)(5) = 15
Area of semicircle = 1/2(3.14)(3^2) = 14.13
Area of figure = 15 + 14.13 = 29.13
Answer
29.13 square units
Answer:
3
Step-by-step explanation:
the answer is 3 if you check very well
First, make 6 into an improper fraction.
6/1
Now multiply the numerators.
6x3=18
Now, the same with the denominators.
1x5=5
18/5
Now make it into a mixed number.
5x3=15
3 and...
18-15=3
3 and 3/5!!
Hope this helped!
Answer:
36 in
Step-by-step explanation:
The ratio of proportionality between the two similar triangles is 1:6, which you can find by dividing the corresponding side length measures from each triangle (3/18 = 4/24). Then you can set up a proportion:
1/6 = 6/x, which you can solve to get x = 36
