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3 years ago

If f(x) = x3 – 2x2, which expression is equivalent to f(i)?

Mathematics

1 answer:

Ahat [919]3 years ago

8 0

Answer:

$2 - i$

Step-by-step explanation:

Substitute i for x. Remeber i means imaginart number.

${i}^{3} - 2 {i}^{2}$

Use the Imaginary number exponents rules

${i}^{2} = - 1$

${i}^{3} = - i$

$i {}^{4} = 1$

Simplify the equation.

$- i - ( - 2)$

$- i + 2$

Write as a complex number in form a+bi

$2 - i$

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9. A circle has an arc of length 56pi that is intercepted by a central angle of 120 degrees. What is the radius of the circle?

SSSSS [86.1K]

Answer:

Part 4) $r=84\ units$

Part 9) $sin(\theta)=-\frac{\sqrt{5}}{3}$

Part 10) $sin(\theta)=-\frac{9\sqrt{202}}{202}$

Step-by-step explanation:

Part 4) A circle has an arc of length 56pi that is intercepted by a central angle of 120 degrees. What is the radius of the circle?

we know that

The circumference of a circle subtends a central angle of 360 degrees

The circumference is equal to

$C=2\pi r$

using proportion

$\frac{2\pi r}{360^o}=\frac{56\pi}{120^o}$

simplify

$\frac{r}{180^o}=\frac{56}{120^o}$

solve for r

$r=\frac{56}{120^o}(180^o)$

$r=84\ units$

Part 9) Given cos(∅)=-2/3 and ∅ lies in Quadrant III. Find the exact value of sin(∅) in simplified form

Remember the trigonometric identity

$cos^2(\theta)+sin^2(\theta)=1$

we have

$cos(\theta)=-\frac{2}{3}$

substitute the given value

$(-\frac{2}{3})^2+sin^2(\theta)=1$

$\frac{4}{9}+sin^2(\theta)=1$

$sin^2(\theta)=1-\frac{4}{9}$

$sin^2(\theta)=\frac{5}{9}$

square root both sides

$sin(\theta)=\pm\frac{\sqrt{5}}{3}$

we know that

If ∅ lies in Quadrant III

then

The value of sin(∅) is negative

$sin(\theta)=-\frac{\sqrt{5}}{3}$

Part 10) The terminal side of ∅ passes through the point (11,-9). What is the exact value of sin(∅) in simplified form?

see the attached figure to better understand the problem

In the right triangle ABC of the figure

$sin(\theta)=\frac{BC}{AC}$

Find the length side AC applying the Pythagorean Theorem

$AC^2=AB^2+BC^2$

substitute the given values

$AC^2=11^2+9^2$

$AC^2=202$

$AC=\sqrt{202}\ units$

$sin(\theta)=\frac{9}{\sqrt{202}}$

simplify

$sin(\theta)=\frac{9\sqrt{202}}{202}$

Remember that

The point (11,-9) lies in Quadrant IV

then

The value of sin(∅) is negative

therefore

$sin(\theta)=-\frac{9\sqrt{202}}{202}$

5 0

3 years ago

Use this figure to find value of FOD

stepladder [879]

Hey there!

BOD is a 90 degrees angle. Make an equation for that angle. 15+12+x=90. Simplify this to 27+x=90. You need to isolate x, so subtract 27 on each side to get x=63. C is the answer.

I hope this helps!

4 0

3 years ago

Read 2 more answers

Which equation represents a line which is perpendicular to the line y = -x + 8?

natima [27]

Two lines are perpendicular between each other if their slopes fulfills the following property

$m_1m_2=-1$

where m1 and m2 represents the slopes of line 1 an 2, respectively.

To find the slope of a line we can write it in the form slope-intercept form

$y=mx+b$

Our original line is

$y=-\frac{1}{8}x+8$

Then its slope is

$m_1=-\frac{1}{8}$

Now we have to find the slope of the second line. Using the first property,

$\begin{gathered} m_1m_2=-1_{} \\ -\frac{1}{8}m_2=-1_{} \\ m_2=(-1)(-8) \\ m_2=8 \end{gathered}$

Then the second line has to have a slope of 8.

The options given to us are:

$\begin{gathered} x+8y=8 \\ x-8y=-56 \\ 8x+y=5 \\ y-8x=4 \end{gathered}$

Then we have to determine which of these options have a slope of 8. To do that we write them in the slope-intercept form:

$\begin{gathered} x+8y=8\rightarrow y=-\frac{1}{8}x+1 \\ x-8y=-56\rightarrow y=\frac{1}{8}x+7 \\ 8x+y=5\rightarrow y=-8x+5 \\ y-8x=4\rightarrow y=8x+4 \end{gathered}$

Once we have the options in the right form, we note that the only one of them that has a slope of 8 is the last one.

Then the line perpendicular to the original one is

$y-8x=4$

8 0

1 year ago

Pls help me my homework is due in a couple hours

Alisiya [41]

Answer:

I don't know spanish but 25% of 80= 20 and 15% of 35.00 is 5.25

7 0

2 years ago

What can you tell about the mean of each

Lilit [14]

Answer: The difference between the mean cost to treat dogs at A New Leash on Life

Animal Clinic and the mean cost to treat cats at A New Leash on Life Animal

Clinic is about 10 times the MAD This is a large difference.

Step-by-step explanation:

I GOT THIS RIGHT! THIS IS THE ANSWER

3 0

3 years ago