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2 years ago

WHAT IS 1+2+3+4+5=? IS IT 15

Mathematics

2 answers:

Tema [17]2 years ago

6 0

Yes it is 15 because 1+2 is 3 3+3=6 6+4=10 and finally 10+5=15

Eduardwww [97]2 years ago

6 0

Answer:

1+2+3+4+5=3+7+5=10+5=15yes it is

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Someeee one?????????????????

Ad libitum [116K]

Answer:

Option B) $a_{n} = 2\cdot 4^{n-1}$

Step-by-step explanation:

The given geometric sequence is

2, 8, 32, 128,....

The general form of a geometric sequence is given by

$a_{n} = a_{1}\cdot r^{n-1}$

Where n is the nth term that we want to find out.

a₁ is the first term in the geometric sequence that is 2

r is the common ratio and can found by simply dividing any two consecutive numbers in the sequence,

$r=\frac{8}{2} = 4$

You can try other consecutive numbers too, you will get the same common ratio

$r=\frac{32}{8} = 4$

$r=\frac{128}{32} = 4$

So the common ratio is 4 in this case.

Substitute the value of a₁ and r into the above general equation

$a_{n} = 2\cdot 4^{n-1}$

This is the general form of the given geometric sequence.

Therefore, the correct option is B

Note: Don't multiply the first term and common ratio otherwise you wont get correct results.

Verification:

$a_{n} = 2\cdot 4^{n-1}$

Lets find out the 2nd term

Substitute n = 2

$a_{2} = 2\cdot 4^{2-1} = 2\cdot 4^{1} = 2\cdot 4 = 8$

Lets find out the 3rd term

Substitute n = 3

$a_{3} = 2\cdot 4^{3-1} = 2\cdot 4^{2} = 2\cdot 16 = 32$

Lets find out the 4th term

Substitute n = 4

$a_{4} = 2\cdot 4^{4-1} = 2\cdot 4^{3} = 2\cdot 64 = 128$

Lets find out the 5th term

Substitute n = 5

$a_{5} = 2\cdot 4^{5-1} = 2\cdot 4^{4} = 2\cdot 256 = 512$

Hence, we are getting correct results!

6 0

3 years ago

A King in ancient times agreed to reward the inventor of chess with one grain of wheat on the first of the 64 squares of a chess

statuscvo [17]

Let's start by visualising this concept.

Number of grains on square:
1 2 4 8 16 ...

We can see that it starts to form a geometric sequence, with the common ratio being 2.

For the first question, we simply want the fifteenth term, so we just use the nth term geometric form:
$T_n = ar^{n - 1}$
$T_{15} = 2^{14} = 16384$

Thus, there are 16, 384 grains on the fifteenth square.

The second question begs the same process, only this time, it's a summation. Using our sum to n terms of geometric sequence, we get:
$S_n = \frac{a(r^{n} - 1)}{r - 1}$
$S_{15} = \frac{2^{15} - 1}{2 - 1}$
$S_{15} = 2^{15} - 1 = 32767$

Thus, there are 32, 767 total grains on the first 15 squares, and you should be able to work the rest from here.

6 0

2 years ago

Read 2 more answers

Alicia drives her car 287.5 miles in 5 hours. What is the constant of proportionality that relates the total number of miles, y,

Sphinxa [80]

Answer:

57.5

Step-by-step explanation:

The constant of proportionality is "k" in the equation ...

y = kx

It can be found from values of x and y using ...

k = y/x

For the given values, it is ...

k = (287.5 mi)/(5 h) = 57.5 mi/h

The constant of proportionality relating miles to hours is 57.5.

5 0

3 years ago

What is the center of (x + 1)2 + (y - 3)2 = 9?

katrin2010 [14]

The equation of a circle with center at (h,k) is
(x-h)^2+(y-k)^2=radius^2

given
(x-(-1))^2+(y-3)^2=9
center is (-1,3)

first option

5 0

2 years ago

baseball card come in packs of a dozen 12 cards matt has 132 baseballcards.how many packs of baseball cards did he buy i need he

Hunter-Best [27]

Well let's see first we have to divide
132 divided by 12 is 11
Now to check and prove your answer we should use the multiplication.
11 times 12 is 132.
So now you have a solid answer with proof behind it.
If u need a sentence you might want it to go something like this;
Matt brought 11 packs of baseball cards since 132 divided by 12 is 11. 12 times 11 is 132 cards.
Hope I helped!

5 0

3 years ago

Read 2 more answers