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3 years ago

Please help me with this please!!!!!!

Mathematics

2 answers:

Masteriza [31]3 years ago

8 0

Best Answer: Look at the discriminant of the quadratic equations to find the number and type of solutions. The discriminant is part of the quadratic formula underneath the square root sign: b^2 - 4ac. If it is positive, then there are two real solutions for that quadratic equation. If the discriminant is 0, then there is one real solution. If the discriminant is positive, then there are two imaginary solutions.

1.) x^2 - 18 = 0
a = 1, b = 0, c = -18

b^2 - 4ac
(0)^2 - 4(1)(-18)
72

ANSWER: 2 real solutions

2.) x^2 + 5x + 7 = 0
a = 1, b = 5, c = 7

b^2 - 4ac
(5)^2 - 4(1)(7)
25 - 28
-3

ANSWER: 0 real solutions

Hope this helps

ASHA 777 [7]3 years ago

7 0

The value of the discriminant b^2 - 4ac will tell you this :-

it = 5^2 - 4*1*7 = -3

which is negative
Therfore there are no real number solutions

B

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Read 2 more answers

A random sample of 16 students selected from the student body of a large university had an average age of 25 years. We want to d

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Answer:

$z=\frac{25-24}{\frac{2}{\sqrt{16}}}=2$

$p_v =2*P(Z>2)=0.0455$

If we compare the p value and the significance level given $\alpha=0.05$ we see that $p_v$ so we can conclude that we have enough evidence to reject the null hypothesis, and we can conclude that the true mean differs from 24 at 5% of significance

Step-by-step explanation:

Data given and notation

$\bar X=25$ represent the sample mean

$\sigma=2$ represent the sample population deviation for the sample

$n=16$ sample size

$\mu_o =24$ represent the value that we want to test

$\alpha=0.05$ represent the significance level for the hypothesis test.

t 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 true mean is different from 24, the system of hypothesis would be:

Null hypothesis: $\mu = 24$

Alternative hypothesis: $\mu \neq 24$

If we analyze the size for the sample is < 30 but we know the population deviation so is better apply a 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:

$z=\frac{25-24}{\frac{2}{\sqrt{16}}}=2$

P-value

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

$p_v =2*P(Z>2)=0.0455$

Conclusion

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