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Fed [463]
3 years ago
9

PLEASE HELP ME!

Mathematics
1 answer:
algol133 years ago
5 0

Step-by-step explanation:

1.\sum_{i=1}^{5}3i

The simplest method is "brute force".  Calculate each term and add them up.

∑ = 3(1) + 3(2) + 3(3) + 3(4) + 3(5)

∑ = 3 + 6 + 9 + 12 + 15

∑ = 45

2.\sum_{k=1}^{4}(2k)^{2}

∑ = (2×1)² + (2×2)² + (2×3)² + (2×4)²

∑ = 4 + 16 + 36 + 64

∑ = 120

3.\sum_{k=3}^{6}(2k-10)

∑ = (2×3−10) + (2×4−10) + (2×5−10) + (2×6−10)

∑ = -4 + -2 + 0 + 2

∑ = -4

4. 1 + 1/4 + 1/16 + 1/64 + 1/256

This is a geometric sequence where the first term is 1 and the common ratio is 1/4.  The nth term is:

a = 1 (1/4)ⁿ⁻¹

So the series is:

\sum_{j=1}^{7}(\frac{1}{4})^{j-1}

5. -5 + -1 + 3 + 7 + 11

This is an arithmetic sequence where the first term is -5 and the common difference is 4.  The nth term is:

a = -5 + 4(n−1)

a = -5 + 4n − 4

a = 4n − 9

So the series is:

\sum_{j=1}^{5}(4j-9)

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Which tiles should be added to the model below to make zero?​
Blizzard [7]

Answer:

6 positive tiles

Step-by-step explanation:

6-6 is zero

7 0
3 years ago
what is the perimeter of the triangle. i do not know how to start this problem. any help will be greatly appreciated :))
xz_007 [3.2K]

Given:

Point F,G,H are midpoints of the sides of the triangle CDE.

FG=9,GH=7,CD=24

To find:

The perimeter of the triangle CDE.

Solution:

According to the triangle mid-segment theorem, the length of the mid-segment of a triangle is always half of the base of the triangle.

FG is mid-segment and DE is base. So, by using triangle mid-segment theorem, we get

\dfrac{1}{2}DE=FG

DE=2(FG)

DE=2(9)

DE=18

GH is mid-segment and CE is base. So, by using triangle mid-segment theorem, we get

\dfrac{1}{2}CE=GH

CE=2(GH)

CE=2(7)

CE=14

Now, the perimeter of the triangle CDE is:

Perimeter=CD+DE+CE

Perimeter=24+18+14

Perimeter=56

Therefore, the perimeter of the triangle CDE is 56 units.

7 0
3 years ago
What is 2 units left 2 units up and 4 units right if you start at 0,0
elena-s [515]
That answer would be 2,2
5 0
3 years ago
Read 2 more answers
Seven less than twice a number is 5
marin [14]
Yes, i believe so because u can count back twice and u will get 5. You could al so do: 7-2=5. Hope this helps
8 0
3 years ago
Kristin is 20 km behind a truck that is driving 90 km/h how long will it take her to catch up to the truck? how far will she go
malfutka [58]
Time taken for Kristin to catch up with the truck will be found using the formula
time=(distance)/(speed)
distance=20 km
speed=90 km/h
thus
time=20/90=2/9 hours

Answer: 2/9 hours
5 0
3 years ago
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