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3 years ago

Solve x

Mathematics

1 answer:

d1i1m1o1n [39]3 years ago

7 0

Step-by-step explanation:

$x^{2} - 4x - 7 = 0$

First, let's move the $7$ to the right-hand side so we can determine what constant we'll need on the left-hand side to complete the square:

$x^{2} - 4x = 7$

From here, since the coefficient of the $x$ term is $-4$ , we know the square will be $(x - 2)$ (since $-2$ it's half of $-4$ ).

To complete this square, we will need to add $(-2)^{2}$ to both sides of the equation:

$x^{2} - 4x + (-2)^2 = 7 + ^{-2}$

$x^{2} - 4x + 4 = 7 + 4$

$(x - 2)^{2} = 11$

Now we can take the square root of both sides to figure out the solutions to $x$ :

$x - 2 = \pm \sqrt{11}$

$x = 2 \pm \sqrt{11}$

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H1: $\sigma \neq 1.34$

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And the critical values with $\alpha/2=0.005$ on each tail are:

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Step-by-step explanation:

Information provided

n = 10 sample size

s= 1.186 the sample deviation

$\sigma_o =1.34$ the value that we want to test

$p_v$ represent the p value for the test

t represent the statistic (chi square test)

$\alpha=0.01$ significance level

Part a

On this case we want to test if the true deviation is 1,34 or no, so the system of hypothesis are:

H0: $\sigma = 1.34$

H1: $\sigma \neq 1.34$

The statistic is given by:

$t=(n-1) [\frac{s}{\sigma_o}]^2$

Part b

The degrees of freedom are given by:

$df = n-1= 10-1=9$

And the critical values with $\alpha/2=0.005$ on each tail are:

$\chi_{\alpha/2}= 1.735, \chi_{1-\alpha/2}= 23.589$

Part c

Replacing the info we got:

$t=(10-1) [\frac{1.186}{1.34}]^2 =7.05$

Part d

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