Ask question

Ask question

All categories

3 years ago

8

Each shelf in one section of the library holds 30 books. There are 9 shelves in that section. How many books will these shelves

hold?

2 answers:

Lina20 [59]3 years ago

5 0

Answer:

270

Step-by-step explanation:

30 times 9 equals 270

natulia [17]3 years ago

5 0

Answer:270

Step-by-step explanation:9x30

You might be interested in

A culture started with 3000 bacteria. After 2 hours it grew to 3300 bacteria. Predict how many bacteria will be present after 16

bixtya [17]

Answer:

$6,430\ bacteria$

Step-by-step explanation:

we have a exponential function of the form

$y=a(1+r)^{x}$

where

y is the population of bacteria

a is the initial value

r is the rate of growth

x is the number of hours

we have

a=3,000 bacteria

$y=3,000(1+r)^{x}$

For x=2, y=3,300

substitute

$3,300=3,000(1+r)^{2}$

$(3,300/3,000)=(1+r)^{2}$

Apply square root both sides

$1+r=\sqrt{3.3/3}$

$r=\sqrt{3.3/3}-1$

$r=0.0488$

$r=4.88\%$

substitute in the equation

$y=3,000(1+0.0488)^{x}$

$y=3,000(1.0488)^{x}$

<u><em>Predict how many bacteria will be present after 16 hours</em></u>

For x=16 hours

substitute

$y=3,000(1.0488)^{16}$

$y=6,430\ bacteria$

6 0

3 years ago

Let a1, a2, a3, ... be a sequence of positive integers in arithmetic progression with common difference

Bezzdna [24]

Since $a_1,a_2,a_3,\cdots$ are in arithmetic progression,

$a_2 = a_1 + 2$

$a_3 = a_2 + 2 = a_1 + 2\cdot2$

$a_4 = a_3+2 = a_1+3\cdot2$

$\cdots \implies a_n = a_1 + 2(n-1)$

and since $b_1,b_2,b_3,\cdots$ are in geometric progression,

$b_2 = 2b_1$

$b_3=2b_2 = 2^2 b_1$

$b_4=2b_3=2^3b_1$

$\cdots\implies b_n=2^{n-1}b_1$

Recall that

$\displaystyle \sum_{k=1}^n 1 = \underbrace{1+1+1+\cdots+1}_{n\,\rm times} = n$

$\displaystyle \sum_{k=1}^n k = 1 + 2 + 3 + \cdots + n = \frac{n(n+1)}2$

It follows that

$a_1 + a_2 + \cdots + a_n = \displaystyle \sum_{k=1}^n (a_1 + 2(k-1)) \\\\ ~~~~~~~~ = a_1 \sum_{k=1}^n 1 + 2 \sum_{k=1}^n (k-1) \\\\ ~~~~~~~~ = a_1 n + n(n-1)$

so the left side is

$2(a_1+a_2+\cdots+a_n) = 2c n + 2n(n-1) = 2n^2 + 2(c-1)n$

Also recall that

$\displaystyle \sum_{k=1}^n ar^{k-1} = \frac{a(1-r^n)}{1-r}$

so that the right side is

$b_1 + b_2 + \cdots + b_n = \displaystyle \sum_{k=1}^n 2^{k-1}b_1 = c(2^n-1)$

Solve for $c$ .

$2n^2 + 2(c-1)n = c(2^n-1) \implies c = \dfrac{2n^2 - 2n}{2^n - 2n - 1} = \dfrac{2n(n-1)}{2^n - 2n - 1}$

Now, the numerator increases more slowly than the denominator, since

$\dfrac{d}{dn}(2n(n-1)) = 4n - 2$

$\dfrac{d}{dn} (2^n-2n-1) = \ln(2)\cdot2^n - 2$

and for $n\ge5$ ,

$2^n > \dfrac4{\ln(2)} n \implies \ln(2)\cdot2^n - 2 > 4n - 2$

This means we only need to check if the claim is true for any $n\in\{1,2,3,4\}$ .

$n=1$ doesn't work, since that makes $c=0$ .

If $n=2$ , then

$c = \dfrac{4}{2^2 - 4 - 1} = \dfrac4{-1} = -4 < 0$

If $n=3$ , then

$c = \dfrac{12}{2^3 - 6 - 1} = 12$

If $n=4$ , then

$c = \dfrac{24}{2^4 - 8 - 1} = \dfrac{24}7 \not\in\Bbb N$

There is only one value for which the claim is true, $c=12$ .

3 0

2 years ago

I WILL MARK YOU AS BRAINLIEST IF YOU ARE CORRECT. Look at the image below.

Masteriza [31]

Answer:

x=8.06

Step-by-step explanation:

find you half base and use PYTHAGORAS THEOREM to find the opposite side (x)

6 0

3 years ago

in there first year josh will be paid $14 and Tillery will be paid $7 after every year they will be giving a raise of $2. is the

Molodets [167]

Answer:

They are Proportional because there will always be a 7 dollar difference

Step-by-step explanation:

Josh is paid 14

Tillery is payed 7$

The relation is proportional

Josh ||| Tillery

___________

14 ||| 7

16 ||| 9

18 ||| 11

20 ||| 13

8 0

3 years ago

Which of the following statements are true? I. -(-6) = 6 and -(-4) > -4 III. 5 + 6 = 11 or 9 - 2 = 11 II. -(-4) < 4 or -10

scoray [572]

IV : 17 > 2 or 6 < 9......these are true....17 is greater then 2 and 6 is less then 9

8 0

3 years ago