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1 year ago

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Marco solves the equation 4sin(3x) + 0.25 ≤ 2sin(3x) − 0.3 by graphing y = 2sin(3x) and y = −0.55. he then locates the intervals

on which 2sin(3x) is less than or equal to −0.55. is marco's solution method valid? explain.

2 answers:

raketka [301]1 year ago

8 0

Help me with this please

ch4aika [34]1 year ago

6 0

Answer:

yes, Marco's method is correct.

The given inequality can be rewritten using the properties of inequality.

You can subtract 2sin(3x) and 0.25 from both sides of the inequality.

Subtracting preserves the direction of the inequality, so 2sin(3x) would be less than or equal to –0.55.

Step-by-step explanation:

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The time until recharge for a battery in a laptop computer under common conditions is normally distributed with mean of 265 minu

pochemuha

Answer:

a) 0.691 = 69.1% probability that a battery lasts more than four hours

b) 25% value = 231

75% value = 299

c) 183 minutes

Step-by-step explanation:

Problems of normally distributed samples are solved using the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the zscore of a measure X is given by:

$Z = \frac{X - \mu}{\sigma}$

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

In this problem, we have that:

$\mu = 265, \sigma = 50$

a) What is the probability that a battery lasts more than four hours?

4 hours = 4*60 = 240 minutes

This is 1 subtracted by the pvalue of Z when X = 240. So

$Z = \frac{X - \mu}{\sigma}$

$Z = \frac{240 - 265}{50}$

$Z = -0.5$

$Z = -0.5$ has a pvalue of 0.309

1 - 0.309 = 0.691

0.691 = 69.1% probability that a battery lasts more than four hours

b) What are the quartiles (the 25% and 75% values) of battery life?

25th percentile:

X when Z has a pvalue of 0.25. So X when Z = -0.675

$Z = \frac{X - \mu}{\sigma}$

$-0.675 = \frac{X - 265}{50}$

$X - 265 = -0.675*50$

$X = 231$

75th percentile:

X when Z has a pvalue of 0.75. So X when Z = 0.675

$Z = \frac{X - \mu}{\sigma}$

$0.675 = \frac{X - 265}{50}$

$X - 265 = 0.675*50$

$X = 299$

25% value = 231

75% value = 299

c) What value of life in minutes is exceeded with 95% probability?

The 100-95 = 5th percentile, which is the value of X when Z has a pvalue of 0.05. So X when Z = -1.645.

$Z = \frac{X - \mu}{\sigma}$

$-1.645 = \frac{X - 265}{50}$

$X - 265 = -1.645*50$

$X = 183$

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2 years ago

Tickets to a baseball game cost $22 each and parking costs $10. What is the equation of the line that represents the cost of att

Reika [66]

x - number of games

22x - cost of x tickets

10 - parking cost

The equation:

$y=22x+10$

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2 years ago

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x^2+1/2x+1/16=4/9 Factor the perfect-square trinomial on the left side of the equation. (x + )² = 4/9

Nezavi [6.7K]

The missing number is the square-root of the constant term on the left-hand-side, which equals sqrt(1/16)=1/sqrt(16)=1/4.
Check:
(x+1/4)^2=x^2+2*(1/4)x+(1/4)^2=x^2+x/2+1/16. ok

Answer: x= 1/4

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1 year ago

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Sum of positive roots of the equation (x2 - 12x + 35) (x2 + 10x + 24) = 504 is

Digiron [165]

Answer:

(3)11

Step-by-step explanation:

We are given that

$(x^2-12x+35)(x^2+10x+24)=504$

We have to find the sum of positive roots of the equation.

$x^2(x^2+10x+24)-12x(x^2+10x+24)+35(x^2+10x+24)=504$

$x^4+10x^3+24x^2-12x^3-120x^2-288x+35x^2+350x+840=504$

$x^4-2x^3-61x^2+62x+840-504=0$

$x^4-2x^3-61x^2+62x+336=0$

Factor of 336

2,3,4,6,8,7,

Let x=2

$2^4-2^4-61(2^2)+62(2)+336\neq0$

x=2 is not the root of equation

x=-2

$(-2)^4-2(-2)^3-61(-2)^2+62(-2)+336=0$

Hence x=-2 is the root of equation.

x+2 is a factor of equation.

x=3

$3^4-2(3^3)-61(3^2)+62(3)+336=0$

Therefore, x=3 is the root of equation.

$(x+2)(x-3)(x^2-x-56)=0$

$(x+2)(x-3)(x^2-8x+7x-56)=0$

$(x+2)(x-3)(x(x-8)+7(x-8))=0$

$(x+2)(x-3)(x-8)(x+7)=0$

$x-8=0\implies x=8$

$x+7=0\implies x=-7$

Positive roots are 3 and 8

Sum of positive roots=3+8=11

Option (3) is true.

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1 year ago

The orbit of the planet Venus is nearly circular. An astronomer develops a model for the orbit in which the sun has coordinates

klio [65]

Since the Venus orbits round the sun, the sun is the center of the circular path of the revolution of the planet, Venus.

Thus, the distance of the planet, Venus fron the sun is given by the distance between the points (0, 0) and (41, 53).

Recall that the distance between two points $(x_1, y_1)$ and $(x_2, y_2)$ is given by $d= \sqrt{(x_2-x_1)^2+(y_2-y_1)^2}$

Thus, the distance between the points (0, 0) and (41, 53) is given by:

$d= \sqrt{(41-0)^2+(53-0)^2} \\ \\ = \sqrt{41^2+53^2} = \sqrt{1,681+2,809} \\ \\ = \sqrt{4,490} =67 \ units$

Given that each unit of the plane represents 1 million miles, therefore, the distance from the sun to the Venus is 67 million miles.

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1 year ago