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3 years ago

Please answer as fast as you can. what is 30 + 5(2x -1) + 20

Mathematics

2 answers:

omeli [17]3 years ago

7 0

Answer:

10x + 55

Hope this helps :)

lozanna [386]3 years ago

5 0

the answer is 40 brainliest plz

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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

3 years ago

1/13

levacccp [35]

Answer:

y=20-3x

Step-by-step explanation:

7 0

3 years ago

Kaitlyn drove 360 miles in 9 hours. If she continues driving at the same speed, how far will she have driven in 11 hours?

stellarik [79]

Answer:

440 miles

Step-by-step explanation:

First, you need to calculate the number of miles per hour. To do this, take the total number of miles traveled and divide it by the number of hours it took. 360/9=40. This means Kaitlyn drove at 40 miles per hour. Then, we need to multiply 40 by 11 to figure out the number of miles she drove in 11 hours because her speed stayed the same. 40*11=440. This means Kaitlyn will have driven 440 miles in 11 hours.

Hope this helps! :)

4 0

2 years ago

Drag each equation to show if it could be a correct first step to solving the equation 8(x + 5) = 56.

cupoosta [38]

Answer:

8x+40=56

Step-by-step explanation:

You have to distribute the 8

Then finish the rest of the problem

7 0

3 years ago

Please help me

galina1969 [7]

Answer:

Your answer is.....

In every big pieces there will be 3 * 1/3 pieces.

So total 12 of 1/3 pieces

Mark it as brainlist answer . follow me for more answer.

Step-by-step explanation:

7 0

3 years ago