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3 years ago

What is 20% of 160?....................

Mathematics

1 answer:

serious [3.7K]3 years ago

4 0

Answer:

20% of 160 is 32

Step-by-step explanation:

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4. Find the sum of all the numbers from 100 to 199 that are not divisible by 13.

Ierofanga [76]

There are 100 numbers in the range 100-199. Find the smallest and largest multiple of 13 in this range. We have

104 = 8•13

195 = 15•13

so there are 15 - 8 + 1 = 8 multiples of 13 between 100 and 199.

Then the sum we want is

$\displaystyle \sum_{k=100}^{199} k - \sum_{\ell=8}^{15}13\ell$

or equivalently,

(100 + 101 + 102 + … + 199) - 13 (8 + 9 + … + 15)

To compute these sums, recall the following formula:

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

Then

$\displaystyle \sum_{k=100}^{199} k = \sum_{k=1}^{199} k - \sum_{k=1}^{99} k = \frac{199\cdot200}2 - \frac{99\cdot100}2 = 14,950$

and

$\displaystyle \sum_{\ell=8}^{15} 13\ell = 13 \left(\sum_{\ell=1}^{15} \ell - \sum_{\ell=1}^7 \ell\right) = 13 \left(\frac{15\cdot16}2 - \frac{7\cdot8}2\right) = 1,196$

which means the sum we want is 14,950 - 1,196 = 13,754.

7 0

2 years ago

Which values represent the first two terms of the sequence a1=2 and an=-2(an-1)^2?

Mars2501 [29]

Hello,

$a_{1}=2$
$a_{n+1}=-2*a_{n}^2$

$a_{1}=2$
$a_{2}=-2*2^{2}=-8$
$a_{3}=-2*(-8)^{2}=-2*64=-128$

Answer C

3 0

3 years ago

Given a≠±b and a^2−b^2/a+b =12, find a−b.

11Alexandr11 [23.1K]

$\dfrac{a^2 - b^2}{a+b} = 12$

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Factorise a² - b² :
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$\dfrac{(a+b)(a-b)}{a+b} = 12$

--------------------------------------------------
Crossed out common factors, (x + a) :
--------------------------------------------------
$a- b = 12$

4 0

4 years ago

Read 2 more answers

Can someone help? will award brainliest

Nina [5.8K]

Answer:

Step-by-step explanation:

The beginning temperature is -12 and then it rises 5 degrees each hour at the end of the game it is 32 degrees.

8 0

2 years ago

Read 2 more answers

Can anyone answer this >?