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2 years ago

Use the discriminant to find the number and type of solution for x^2+6x=-9

Mathematics

1 answer:

likoan [24]2 years ago

6 0

Answer:

D = 0; one real root

Step-by-step explanation:

Discriminant Formula:

$\displaystyle \large{D = {b}^{2} - 4ac}$

First, arrange the expression or equation in ax^2+bx+c = 0.

$\displaystyle \large{ {x}^{2} + 6x = - 9}$

Add both sides by 9.

$\displaystyle \large{ {x}^{2} + 6x + 9 = - 9 + 9} \\ \displaystyle \large{ {x}^{2} + 6x + 9 = 0}$

Compare the coefficients so we can substitute in the formula.

$\displaystyle \large{a {x}^{2} + bx + c = {x}^{2} + 6x + 9 }$

a = 1
b = 6
c = 9

Substitute a = 1, b = 6 and c = 9 in the formula.

$\displaystyle \large{D = {6}^{2} - 4(1)(9)} \\ \displaystyle \large{D = 36 - 36} \\ \displaystyle \large{D = 0}$

Since D = 0, the type of solution is one real root.

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Experian would like to test the hypothesis that the average credit score for an adult in Virginia is different from the average

aliya0001 [1]

Answer:

a. We fail to reject the hypothesis that the average credit score for an adult in Virginia is different from the average credit score for an adult in North Carolina at the significance level of 0.05.

b. The 95% confidence interval for the true difference of means is -2.2468 and 36.2468. There is a probability of 95% that the true difference of means $\mu_{1}-\mu_{2}$ is between -2.2468 and 36.2468. This confidence interval contains the number 0, this is consistent with the results we got in a. Because we fail to reject the hypothesis that the average credit score for an adult in Virginia is different from the average credit score for an adult in North Carolina at the significance level of 0.05.

Step-by-step explanation:

Let $\mu_{1}-\mu_{2}$ be the true difference between the average credit score for an adult in Virginia and the average credit score for an adult in North Carolina. We have the large sample sizes $n_{1} = 40$ and $n_{2} = 35$ , the unbiased point estimate for $\mu_{1}-\mu_{2}$ is $\bar{x}_{1} - \bar{x}_{2}$ , i.e., 699-682 = 17.

The standard error is given by $\sqrt{\frac{\sigma^{2}_{1}}{n_{1}}+\frac{\sigma^{2}_{2}}{n_{2}}}$ , i.e.,

$\sqrt{\frac{(44)^{2}}{40}+\frac{(41)^{2}}{35}}$ = 9.8198.

a. We want to test $H_{0}: \mu_{1}-\mu_{2} = 0$ vs $H_{1}: \mu_{1}-\mu_{2} \neq 0$ (two-tailed alternative). The rejection region is given by RR = {z | z < -1.96 or z > 1.96} where -1.96 and 1.96 are the 2.5th and 97.5th quantiles of the standard normal distribution respectively. The test statistic is $Z = \frac{\bar{x}_{1} - \bar{x}_{2}-0}{\sqrt{\frac{\sigma^{2}_{1}}{n_{1}}+\frac{\sigma^{2}_{2}}{n_{2}}}}$ and the observed value is $z_{0} = \frac{17}{9.8198} = 1.7312$ . Because 1.7312 does not fall inside RR, we fail to reject the null hypothesis.

b. The endpoints for a 95% confidence interval for $\mu_{1}-\mu_{2}$ is given by $17\pm (z_{0.05/2})9.8198$ , i.e., $17\pm (z_{0.025})9.8198$ where $z_{0.025}$ is the 2.5th quantile of the standard normal distribution, i.e., -1.96, so, we have 17-(1.96)(9.8198) and 17+(1.96)(9.8198), i.e., -2.2468 and 36.2468. There is a probability of 95% that the true difference of means $\mu_{1}-\mu_{2}$ is between -2.2468 and 36.2468. This confidence interval contains the number 0, this is consistent with the results we got in a. Because we fail to reject the hypothesis that the average credit score for an adult in Virginia is different from the average credit score for an adult in North Carolina at the significance level of 0.05.

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3 years ago

Michael rotates ABC to form the image A'B'C'. The table shows the corresponding vertices for ABC and AA'B'C'. What degree of rot

babunello [35]

Answer:

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Step-by-step explanation:

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The slope of OA = 3/2 and the slope of OA' = -2/3.

The product of these slopes = 3/2 * -2/3 = -1 so the lines are perpendicular - that is the line has passed through an angle of 90 degrees.

A similar result occurs if we consider points B, C and D.

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Step-by-step explanation:

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3 years ago

Use the discriminant to find the number and type of solution for x^2+6x=-9​

Use the discriminant to find the number and type of solution for x^2+6x=-9