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3 years ago

Does the following infinite series have a sum or not and does it converge or diverge?

Mathematics

1 answer:

iren [92.7K]3 years ago

3 0

Answer:

Step-by-step explanation:

Please present these numbers as a list: 7, -21, 63, -189, ....

Otherwise it appears that you are adding them up, which is not the case.

We can tell that this is a geometric series because each new number is -3 times the previous number: -3(7) = -21, -3(-21) = 63, and so on. Let r = -3 and a = first number = 7.

The sum of an infinite geometric series exists if and only if |r} < 1. Here, |-3|, or 3, so in this case the sum of the series does not exist. That is, the series diverges.

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Find the area of a quadrilateral ABCD in which AB = 3 cm, BC = 4 cm, CD = 4 cm, DA = 5 cm and AC = 5 cm.

melamori03 [73]

Answer:

$6+2\sqrt{21}\:\mathrm{cm^2}\approx 15.17\:\mathrm{cm^2}$

Step-by-step explanation:

The quadrilateral ABCD consists of two triangles. By adding the area of the two triangles, we get the area of the entire quadrilateral.

Vertices A, B, and C form a right triangle with legs $AB=3$ , $BC=4$ , and $AC=5$ . The two legs, 3 and 4, represent the triangle's height and base, respectively.

The area of a triangle with base $b$ and height $h$ is given by $A=\frac{1}{2}bh$ . Therefore, the area of this right triangle is:

$A=\frac{1}{2}\cdot 3\cdot 4=\frac{1}{2}\cdot 12=6\:\mathrm{cm^2}$

The other triangle is a bit trickier. Triangle $\triangle ADC$ is an isosceles triangles with sides 5, 5, and 4. To find its area, we can use Heron's Formula, given by:

$A=\sqrt{s(s-a)(s-b)(s-c)}$ , where $a$ , $b$ , and $c$ are three sides of the triangle and $s$ is the semi-perimeter ( $s=\frac{a+b+c}{2}$ ).

The semi-perimeter, $s$ , is:

$s=\frac{5+5+4}{2}=\frac{14}{2}=7$

Therefore, the area of the isosceles triangle is:

$A=\sqrt{7(7-5)(7-5)(7-4)},\\A=\sqrt{7\cdot 2\cdot 2\cdot 3},\\A=\sqrt{84}, \\A=2\sqrt{21}\:\mathrm{cm^2}$

Thus, the area of the quadrilateral is:

$6\:\mathrm{cm^2}+2\sqrt{21}\:\mathrm{cm^2}=\boxed{6+2\sqrt{21}\:\mathrm{cm^2}}$

4 0

3 years ago

Please answer 5x < 10?

Natalka [10]

Answer:

Step-by-step explanation:

Solving inequalities is easy, you just need to follow the standard rules of algebra. Also, when multiplying or dividing by a negative number, the inequality sign is reversed.

Step 1: Divide by 5

x < 2

Step 2: Check

5(1) < 10

5 < 10✔️

Step 3: Check Again

Since an inequality has multiple solutions, it is important to check at least 2, to determine if the entire range of solutions is true.

5(-6) < 10

-30 < 10✔️

Step 4: Verified Answer

x < 2

I'm always happy to help :)

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Step-by-step explanation:

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