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3 years ago

What should be done to solve the following equation d - 8 equals 9

Mathematics

2 answers:

Nitella [24]3 years ago

6 0

Answer:

What should be done is you add 8 on both sides and then d=17

Step-by-step explanation:

mr Goodwill [35]3 years ago

4 0

You have to do balanced steps and then add 8 on both sides to d-8=9. Then you should get an answer of d=17.

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Use a calculator to solve this problem: 28 + 27 × 36

LiRa [457]

Answer:

1000

Step-by-step explanation:

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3 years ago

Read 2 more answers

Help me with trigonometry

poizon [28]

Answer:

See below

Step-by-step explanation:

It has something to do with the Weierstrass substitution, where we have

$\int\, f(\sin(x), \cos(x))dx = \int\, \dfrac{2}{1+t^2}f\left(\dfrac{2t}{1+t^2}, \dfrac{1-t^2}{1+t^2} \right)dt$

First, consider the double angle formula for tangent:

$\tan(2x)= \dfrac{2\tan(x)}{1-\tan^2(x)}$

Therefore,

$\tan\left(2 \cdot\dfrac{x}{2}\right)= \dfrac{2\tan(x/2)}{1-\tan^2(x/2)} = \tan(x)=\dfrac{2t}{1-t^2}$

Once the double angle identity for sine is

$\sin(2x)= \dfrac{2\tan(x)}{1+\tan^2(x)}$

we know $\sin(x)=\dfrac{2t}{1+t^2}$ , but sure, we can derive this formula considering the double angle identity

$\sin(x)= 2\sin\left(\dfrac{x}{2}\right)\cos\left(\dfrac{x}{2}\right)$

Recall

$\sin \arctan t = \dfrac{t}{\sqrt{1 + t^2}} \text{ and } \cos \arctan t = \dfrac{1}{\sqrt{1 + t^2}}$

Thus,

$\sin(x)= 2 \left(\dfrac{t}{\sqrt{1 + t^2}}\right) \left(\dfrac{1}{\sqrt{1 + t^2}}\right) = \dfrac{2t}{1 + t^2}$

Similarly for cosine, consider the double angle identity

Thus,

$\cos(x)= \left(\dfrac{1}{\sqrt{1 + t^2}}\right)^2- \left(\dfrac{t}{\sqrt{1 + t^2}}\right)^2 = \dfrac{1}{t^2+1}-\dfrac{t^2}{t^2+1} =\dfrac{1-t^2}{1+t^2}$

Hence, we showed $\sin(x) \text { and } \cos(x)$

======================================================

$5\cos(x) =12\sin(x) +3, x \in [0, 2\pi ]$

Solving

$5\,\overbrace{\frac{1-t^2}{1+t^2}}^{\cos(x)} = 12\,\overbrace{\frac{2t}{1+t^2}}^{\sin(x)}+3$

$\implies \dfrac{5-5t^2}{1+t^2}= \dfrac{24t}{1+t^2}+3 \implies \dfrac{5-5t^2 -24t}{1+t^2}= 3$

$\implies 5-5t^2-24t=3\left(1+t^2\right) \implies -8t^2-24t+2=0$

$t = \dfrac{-(-24)\pm \sqrt{(-24)^2-4(-8)\cdot 2}}{2(-8)} = \dfrac{24\pm 8\sqrt{10}}{-16} = \dfrac{3\pm \sqrt{10}}{-2}$

$t=-\dfrac{3+\sqrt{10}}{2}\\t=\dfrac{\sqrt{10}-3}{2}$

Just note that

$\tan\left(\dfrac{x}{2}\right) = \dfrac{3\pm 8\sqrt{10}}{-2}$

and $\tan\left(\dfrac{x}{2}\right)$ is not defined for $x=k\pi , k\in\mathbb{Z}$

6 0

2 years ago

1 kilometer:3 meter on the map. The distance from the school to the park is 4 meters on the map how many actual kilometers is it

Neporo4naja [7]

Answer:

4 km

Step-by-step explanation:

1000m:3m = 4000m:12m

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3 years ago

A shipment of 105 Otter box covers for I-phones has arrived. The total invoice (excluding tax, shipping, etc.) is $3,849.75.

bezimeni [28]

3,849.75 ÷ 49.95 = 77 (Calculator)

Sense you would like it explained than the question is asking how many otter box Defender Covers where shipped in that price. So when you have that they want the amount of Otter Box Defenders than you divide the amount paid for the shipment with the amount of the otter box defender price.

I hope this is helpful.

3 0

3 years ago

The population of a small town in Alabama is 382 people. If the growth rate is 0.7%, what will its population be in 30 years?

goldenfox [79]

Formula for growth:

y = initial • (percent growth + 1)^time/frequency of growth

So, since initial population is 382

Percent growth is 0.007

The time is 30 years

And it goes it by .07% every 1 year,

y = 382 • (1.007)^30/1

y= 470.9203732 people

Since we can’t have 0.9 of a person, the population after 30 years will be 470 people.

4 0

2 years ago