What is the total surface area ?

Identify the graph of 9X^2+4xy+5y^2-40=0 and find theta to the nearest degree.

lubasha [3.4K]

Answer:

The answer is ellipse; 23° to the nearest degree ⇒ answer (d)

Step-by-step explanation:

* At first lets talk about the general form of the conic equation

- Ax² + Bxy + Cy² + Dx + Ey + F = 0

∵ B² - 4AC < 0 , if a conic exists, it will be either a circle or an ellipse.

∵ B² - 4AC = 0 , if a conic exists, it will be a parabola.

∵ B² - 4AC > 0 , if a conic exists, it will be a hyperbola.

* Now we will study our equation:

- 9x² + 4xy + 5y² - 40 = 0

∵ A = 9 , B = 4 , 5 = 5

∴ B² - 4 AC = (4)² - 4(9)(5) = -164 < 0

∴ B² - 4AC < 0

∴ If a conic exists, it will be either a circle or an ellipse.

* To find the type of the graph lets check;

- If A and C are nonzero, have the same sign, and are not

equal to each other, then the graph is an ellipse.

- If A and C are equal and nonzero and have the same

sign, then the graph is a circle.

∵ A and C have same signs and are not equal

∴ The graph is an ellipse

* If we have term xy ⇒ B ≠ 0

∴ The graph is rotate by angle Ф

* To find the angle of rotation use the rule:

- cot(2Ф) = (A - C)/B

∵ A = 9 , B = 4 , C = 5

∴ cot(2Ф) = (9 - 5)/4 = 4/4 = 1

∴ tan(2Ф) = 1

∴ 2Ф = 45°

∴ Ф = 22.5° ≅ 23° to the nearest degree

* The answer is ellipse; with angle of rotation = 23°

4 0

4 years ago

How much money would you need to deposit today at 7% annual interest

Monica [59]

Answer:

$33,090.

Step-by-step explanation:

The formula is A = P( 1 + r/2)^2n so we have:

50,000 = P(1 + 0.07/2)^(6*2)

50000 = P * 1.035^12

P = 50000/ 1.035^12

= $33,090 to the nearest dollar.

4 0

3 years ago

I need the answer for number 3.

deff fn [24]

Answer:

0.12

Step-by-step explanation:

15 divided by 125 is equal to 0.12

6 0

3 years ago

A 9-year-old girl did a science fair experiment in which she tested professional touch therapists to see if they could sense he

Orlov [11]

Answer:

We conclude that the the touch therapists does not use a method equivalent to random guesses.

Yes, the results suggest that touch therapists are effective.

Step-by-step explanation:

We are given that in a 9-year-old girl did a science fair experiment in which she tested professional touch therapists to see if they could sense her energy field.

Among 264264 trials, the touch therapists were correct 105105 times.

Let p = proportion that touch therapists uses a random guess method.

Here, random guess means; p = 50%

So, Null Hypothesis, $H_0$ : p = 50% {means that the touch therapists use a method equivalent to random guesses}

Alternate Hypothesis, $H_A$ : p $\neq$ 50% {means that the touch therapists does not use a method equivalent to random guesses}

The test statistics that would be used here One-sample z proportion statistics;

T.S. = $\frac{\hat p-p}{\sqrt{\frac{\hat p(1-\hat p)}{n} } }$ ~ N(0,1)

where, $\hat p$ = sample proportion of touch therapists were correct = $\frac{105}{264}$ = 0.39

n = sample of trials = 264

So, test statistics = $\frac{\frac{105}{264} -0.50}{\sqrt{\frac{\frac{105}{264}(1-\frac{105}{264})}{264} } }$

= -3.395

The value of z test statistics is -3.395.

Now, at 0.05 significance level the z table gives critical value of -1.96 and 1.96 for two-tailed test. Since our test statistics does not lie within the range of critical values of z, so we have sufficient evidence to reject our null hypothesis as it will in the rejection region due to which we reject our null hypothesis.

Therefore, we conclude that the the touch therapists does not use a method equivalent to random guesses.

Yes, the results suggest that touch therapists are effective.

3 0

3 years ago

The following table shows a proportional relationship between mmm and nnn.

Marina CMI [18]

Answer:

70707mmm = 111nnn

Step-by-step explanation:

Using the basic equation of a line:

y = mx + c;. where m is slope and c is intercept on y axis.

Let mmm = y and nnn = x

(i) 333 = 212121m + c

(ii) 555 = 353535m + c

Making c the subject of the formula in both (i) and (ii)

c = 333 - 212121m = 555 - 353535m

353535m -212121m = 555 - 333

141414m = 222

m = 111/70707

Substitute in (i) above

c = 333 -333 = 0

Hence; y = 111/70707x + c

Finally, mmm = 111/70707 nnn

i.e. 70707mmm = 111nnn

Hope this helps.

5 0

3 years ago

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