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Leno4ka [110]
3 years ago
10

What is the sum of the geometric series in which a1 = −5, r = 3, and an = −405?

Mathematics
1 answer:
xxMikexx [17]3 years ago
4 0
a_1=-5;\ r=3;\ a_n=-405\\\\a_n=a_1r^{n-1}\\\\subtitute\\\\-5\cdot3^{n-1}=-405\ \ \ |divide\ both\ sides\ by\ (-5)\\\\3^{n-1}=81\\\\3^{n-1}=3^4\iff n-1=4\to n=5\\\\S_n=\dfrac{a_1(1-r^n)}{1-r}\\\\S_5=\dfrac{-5(1-3^5)}{1-3}=\dfrac{-5(1-243)}{-2}=\dfrac{5\cdot(-242)}{2}=5\cdot(-121)=-605\\\\\\Answer:\boxed{S_5=-605}
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453.59 multiplied by 10 carry out to 4 decimal places
zvonat [6]
I believe it should be 45.3590 if not try this answer 453.590 I believe
3 0
3 years ago
Read 2 more answers
Solve for x. Round to the nearest hundredth.
zlopas [31]

<u>Given </u>that the length of the hypotenuse is 8 and the angle is 42°

The length of the one leg of the triangle is x.

We need to determine the value of x.

<u>Value of x:</u>

The value of x can be determined using the trigonometric ratio.

Thus, we have;

sin \ \theta=\frac{opp}{hyp}

Substituting the values, we get;

sin \ 42^{\circ}=\frac{x}{8}

Multiplying both sides of the equation by 8, we get;

sin \ 42^{\circ}\times8=x

Simplifying, we get;

0.669 \times 8=x

      5.352\approx x

Therefore, the value of x is 5.35(app.)

Hence, Option A is the correct answer.

8 0
3 years ago
(TEN POINTS)
Rainbow [258]
F(-1)= -3 is (-1,-3) and f(2) = 6 is (2,6) where f(x) = y
y=mx + b is the slope-intercept form whereas m equals the slope (rate of change) and b equals the y-intercept (initial amount/what y is when x is 0.)

First, we need to find the slope between the two points (-1,-3) and (2,6). To find the slope we could use one of it's formulas \frac{y^2 - y^1}{x^2 - x^1}.  
1. (-1,-3)
2. (2,6)
\frac{6 - -3}{2 - -1} → \frac{9}{3} → \frac{3}{1}

The slope is 3 (\frac{3}{1}). Thusly, y = 3x + b

To find out the y-intercept, we can reverse the slope. [Note: This \frac{3}{1} is in \frac{rise}{run} where rise is 'y' and run is 'x'. Reversed would be \frac{-3}{-1} ]. Take the second ordered pair and use our reversed slope on it until we get 0 for x. 

(2, 6) ⇒ (2 - 1, 6 -3) ⇒ (1, 3) ⇒ (0,0)

Y-intercept is 0. Therefore, y= 3x + 0 [NOTE: y = f(x), so if you want it in function notation form it's just f(x) = 3x + 0.]
6 0
3 years ago
Can anyone solve this, my teacher is still teaching through online learning and geometry is too confusing
malfutka [58]

Answer:

its too small to see

Step-by-step explanation:

7 0
3 years ago
A rectangular prism and a triangular prism each have a volume of 210 cubic meters. find possible dimensions for each prism.
Evgesh-ka [11]
An interesting question! Let's take a look at the rectangular prism first.

[Rectangular Prism]
We know that the formula for the volume of a rectangular prism is:
volume = length * width * height

or more simply
V = L*W*H

All we know is that the volume is 210 cubic meters. We can choose whatever we want for the dimensions to force it to work! We're free to do what we want!
210 = L*W*H

I like 10, that's a nice number. Let's make L = 10.
210 = 10*W*H

Hmm... but now I need W*H to be 21 (think about it, make sure you get why I say that). Well, how about W = 7 and H = 3? That should work.
210 = 10*7*3

It checks! Possible dimensions for the rectangular prism are L = 10 meters, W = 7 meters, and H = 3 meters. There are many other choices of course, but this is a possible choice.

[Triangular Prism]
Same idea, different formula. For a triangular prism, the volume is
V = 1/2 * L*W*H

But the volume is still 210 cubic meters, so we just have
210 = 1/2 * L*W*H

So, one of our dimensions is going to be cut in half. Why don't we just double L to make up for it? 
210 = 1/2*(20)*W*H

And we can leave W and H the same
210 = 1/2*20*7*3

Check that it works! A possible choice is L = 20 meters, W = 7 meters and H = 3 meters.

We're done!

5 0
3 years ago
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