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blagie [28]
3 years ago
9

Is (4,-3) a solution to this system? 3x-3y=21 5x+4y=24

Mathematics
2 answers:
Elena-2011 [213]3 years ago
8 0

Welcome to Brainly!

We have the following system of linear equations:

3x-3y=21

5x+4y=24

We could solve this system through elimination: Multiply the first equation by 5 and the second equation by -3. When you add together the results, x will drop out. This is a great approach.

But you could take a short cut by subst. the coordinates (4,-3) into both of the given linear equations. IF both equations are true after this substitution, then you know that (4,-3) is a solution. Let's try it:

3(4) - 3(-3) = 21 => 12 + 9 = 21. This is true. But we must ALSO check whether (4,-3) satisfies 5x+4y=24: 5(4) + 4(-3) = 24 => 20 - 12 = 12. This is NOT equal to 24, so we must conclude that (4,-3) is NOT a solution of this system of linear equations.


Arturiano [62]3 years ago
7 0
No it is not. although it fits the first equation, it doesn’t fit the second.
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3 years ago
A certain pen has been designed so that true average writing lifetime under controlled conditions (involving the use of a writin
Morgarella [4.7K]

Answer:

(a) We reject our null hypothesis.

(b) We fail to reject our null hypothesis.

(c) We fail to reject our null hypothesis.

Step-by-step explanation:

We are given that a certain pen has been designed so that true average writing lifetime under controlled conditions (involving the use of a writing machine) is at least 10 hr.

A random sample of 18 pens is selected.

<u><em>Let </em></u>\mu<u><em> = true average writing lifetime under controlled conditions</em></u>

So, Null Hypothesis, H_0 : \mu \geq 10 hr   {means that the true average writing lifetime under controlled conditions is at least 10 hr}

Alternate Hypothesis, H_A : \mu < 10 hr    {means that the true average writing lifetime under controlled conditions is less than 10 hr}

<u>The test statistics that is used here is one-sample t test statistics;</u>

                           T.S. = \frac{\bar X -\mu}{\frac{s}{\sqrt{n} } }  ~ t_n_-_1

where, \bar X = sample mean

             s = sample standard deviation

             n = sample size of pens = 18

          n - 1 = degree of freedom = 18 -1 = 17

<u>Now, the decision rule based on the critical value of t is given by;</u>

  • If the value of test statistics is more than the critical value of t at 17 degree of freedom for left-tailed test, then <u>we will not reject our null hypothesis</u> as it will not fall in the rejection region.
  • If the value of test statistics is less than the critical value of t at 17 degree of freedom for left-tailed test, then <u>we will reject our null hypothesis</u> as it will fall in the rejection region.

(a) Here, test statistics, t = -2.4 and level of significance is 0.05.

<em>Now, at 0.05 significance level, the t table gives critical value of -1.74 at 17 degree of freedom.</em>

Here, clearly the value of test statistics is less than the critical value of t as -2.4 < -1.74, so we reject our null hypothesis.

(b) Here, test statistics, t = -1.83 and level of significance is 0.01.

<em>Now, at 0.051 significance level, the t table gives critical value of -2.567 at 17 degree of freedom.</em>

Here, clearly the value of test statistics is more than the critical value of t as -2.567 < -1.83, so we fail to reject our null hypothesis.

(c) Here, test statistics, t = 0.57 and level of significance is not given so we assume it to be 0.05.

<em>Now, at 0.05 significance level, the t table gives critical value of -1.74 at 17 degree of freedom.</em>

Here, clearly the value of test statistics is more than the critical value of t as  -1.74 < 0.57, so we fail to reject our null hypothesis.

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What would the equation be for the points (0,-2) and (2,6) be? (SLOPE INTERCEPT FORM y=mx+b)
Paladinen [302]

Answer:

Slope m=4

Step-by-step explanation:

m=(y2-y1)/(x2-x1)

We have A(0,-2)->x1=0, y1=-2

B(2,6)->x2=2, y2=6

7 0
1 year ago
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