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never [62]
3 years ago
6

Use the Quadratic Formula to find the exact solutions of x2 + 7x − 4 = 0. x equals negative b plus or minus the square root of b

squared minus 4 times a times c, all over 2 times a x equals negative 7 plus or minus the square root of 33, all over 2 x equals negative 7 plus or minus the square root of 65, all over 2 x equals 7 plus or minus the square root of 65, all over 2 x equals 7 plus or minus the square root of 33, all over 2
Mathematics
2 answers:
Misha Larkins [42]3 years ago
8 0

Answer:

Option 2

x equals negative 7 plus or minus the square root of 65, all over 2

Step-by-step explanation:

x² + 7x - 4 = 0

x = [-b +/- sqrt(b²-4ac)]/2a

x = [-7 +/- sqrt(7² - 4(1)(-4)]/2

x = [-7 +/- sqrt(65)]/2

Ket [755]3 years ago
6 0

Answer:

B

Step-by-step explanation:

Our equation is x² + 7x - 4 = 0. We need to use the quadratic formula, which states that for a quadratic formula of the form ax² + bx + c = 0, then the zeroes/solutions are: x=\frac{-b+\sqrt{b^2-4ac} }{2a} or x=\frac{-b-\sqrt{b^2-4ac} }{2a}.

Here, a = 1, b = 7, and c = -4. Plug these in:

x=\frac{-b+\sqrt{b^2-4ac} }{2a}

x=\frac{-7+\sqrt{7^2-4*1*(-4)} }{2*1}=\frac{-7+\sqrt{49+16} }{2} =\frac{-7+\sqrt{65} }{2}

OR

x=\frac{-b-\sqrt{b^2-4ac} }{2a}

x=\frac{-7-\sqrt{7^2-4*1*(-4)} }{2*1}=\frac{-7-\sqrt{49+16} }{2} =\frac{-7-\sqrt{65} }{2}

Thus, the answer is B.

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Part A: equations B and D are true

Part B: expression B is equal to tan(g)

Step-by-step explanation:

In the given triangle, sin(g) = cos(h) and cos(g) = sin(h).

___

Part A

Based on the above, selection B is true.

Based on the above, the equation of D becomes: sin(h)+sin(g) = sin(g) +sin(h), which is true.

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4 0
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A data set lists earthquake depths. The summary statistics arenequals=500500​,x overbarxequals=5.435.43​km,sequals=4.864.86km. U
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Answer:

C. H 0​:μ=5.00km   H1​:μ≠5.00km

z=\frac{5.43-5.00}{\frac{4.86}{\sqrt{500}}}=1.978    

p_v =2*P(z>1.978)=0.048

If we compare the p value and the significance level given \alpha=0.01 we see that p_v>\alpha so we can conclude that we have enough evidence to FAIL to reject the null hypothesis, so we can conclude that the true mean is nto significantly different from 5.00.    

Step-by-step explanation:

Some previous concepts

The p-value is the probability of obtaining the observed results of a test, assuming that the null hypothesis is correct.

A z-test for one mean "is a hypothesis test that attempts to make a claim about the population mean(μ)".

The null hypothesis attempts "to show that no variation exists between variables or that a single variable is no different than its mean"

The alternative hypothesis "is the hypothesis used in hypothesis testing that is contrary to the null hypothesis"

Data given and notation    

\bar X=5.43 represent the average for the sample

s=4.86 represent the sample standard deviation for the sample    

n=500 sample size    

\mu_o =5.00 represent the value that we want to test  

\alpha=0.01 represent the significance level for the hypothesis test.  

z would represent the statistic (variable of interest)    

p_v represent the p value for the test (variable of interest)

State the null and alternative hypotheses.      

We need to conduct a hypothesis in order to check if the population mean is equal to 5.00, the system of hypothesis would be:    

Null hypothesis:\mu = 5.00    

Alternative hypothesis:\mu \neq 5.00    

Since the sample size >30 and large, the estimator for the population deviation would be s, and we can use the z test to compare the actual mean to the reference value, and the statistic is given by:    

z=\frac{\bar X-\mu_o}{\frac{\sigma}{\sqrt{n}}} (1)    

z-test: "Is used to compare group means. Is one of the most common tests and is used to determine if the mean is (higher, less or not equal) to an specified value".

Calculate the statistic    

We can replace in formula (1) the info given like this:    

z=\frac{5.43-5.00}{\frac{4.86}{\sqrt{500}}}=1.978    

P-value    

Since is a two tailed test the p value would be:    

p_v =2*P(z>1.978)=0.048

In Excel we can us ethe following formula to find the p value "=2*(1-NORM.DIST(1.978;0;1;TRUE))"  

Conclusion    

If we compare the p value and the significance level given \alpha=0.01 we see that p_v>\alpha so we can conclude that we have enough evidence to FAIL to reject the null hypothesis, so we can conclude that the true mean is nto significantly different from 5.00.    

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Answer:

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And if already says 22 students have pets, therefore the answer is

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