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mr_godi [17]
3 years ago
10

What is the answer to the system of equations problem 3x=2y+10 9y=3x-7

Mathematics
1 answer:
Gemiola [76]3 years ago
8 0
Solving:

\left \{ {{3x = 2y + 10} \atop {9y = 3x-7}} \right.
<span>Organize by putting the unknowns left and right the numbers without letter, changing the signal when changing sides.
</span>\left \{ {{3x-2y=10\:(I)} \atop {-3x+9y=-7\:(II)}} \right.
<span>Eliminate opposites (+ 3x and -3x)
</span>\left \{ {{\diagup\!\!\!\!3x-2y=10} \atop {-\diagup\!\!\!\!3x+9y=-7}} \right.
\left \{ {{-2y=10} \atop {9y=-7}} \right.
----------------------------
7y = 3
\boxed{y =  \frac{3}{7} }

<span>Now substitute the found value "y" in the first equation:
</span>3x-2y=10\:(I)
3x-2* \frac{3}{7} =10
3x- \frac{6}{7} = 10
\frac{21x}{\diagup\!\!\!\!7} - \frac{6}{\diagup\!\!\!\!7} = \frac{70}{\diagup\!\!\!\!7}
21x - 6 = 70
21x = 70 + 6
21x = 76
\boxed{x =  \frac{76}{21} }

Answer:
(x,y) = ( \frac{76}{21} ,  \frac{3}{7} )\end{array}}\qquad\quad\checkmark


<span>
Taking the truth proof
</span>
3x - 2y = 10\:(I)
3* \frac{76}{21} - 2* \frac{3}{7} = 10
\frac{228}{21} -  \frac{6}{7} = 10
\frac{1596-126}{147} = 10
\frac{1470}{147} = 10
10 = 10\:(TRUE)






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Step-by-step explanation:

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4 0
3 years ago
An equilateral triangle has sides 8 units long. An equilateral triangle with sides 4 units long is cut off at the top, leaving a
Darina [25.2K]

Answer:

1:3

Step-by-step explanation:

Please study the diagram briefly to understand the concept.

First, we determine the height of the isosceles trapezoid using Pythagoras theorem.

4^2=2^2+h^2\\h^2=16-4\\h^2=12\\h=\sqrt{12}\\ h=2\sqrt{3}$ units

The two parallel sides of the trapezoid are 8 Inits and 4 units respectively.

Area of a trapezoid =\dfrac12 (a+b)h

Area of the trapezoid

=\dfrac12 (8+4)*2\sqrt{3}\\=12\sqrt{3}$ Square Units

For an equilateral triangle of side length s.

Area  =\dfrac{\sqrt{3}}{4}s^2

Side Length of the smaller triangle, s= 4 Units

Therefore:

Area of the smaller triangle

=\dfrac{\sqrt{3}}{4}*4^2\\=4\sqrt{3}$ Square units

Therefore, the ratio of the area of the smaller triangle to the area of the trapezoid

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7 0
4 years ago
The accounting department analyzes the variance of the weekly unit costs reported by two production departments. A sample of cos
madreJ [45]

Answer:

F=\frac{s^2_2}{s^2_1}=\frac{5.4}{2.3}=2.348

p_v =2*P(F_{15,15}>2.348)=0.109

And we can use the following excel code to find the p value:"=2*(1-F.DIST(2.348,15,15,TRUE))"

Since the p_v > \alpha we have enough evidence to FAIL to reject the null hypothesis. And we can say that we don't have enough evidence to conclude that the variation is different between the two groups at 10% of significance.  

Step-by-step explanation:

Assuming the following question :"The accounting department analyzes the variance of the weekly unit costs reported by two  production departments. Asample of 16 cost reports for each of the two departments shows  cost variances of 2.3 and 5.4, respectively. Is this sample sufficient to conclude that the two  production departments differ in terms of unit cost variance? Use α= .10."

Data given and notation  

n_1 = 16 represent the sampe size for sample 1

n_2 =16 represent the sample size for sample 2

s^2_1 = 2.3 represent the sample variance for sample 1

s^2_2 = 5.4 represent the sample variance for sample 2

\alpha=0.1 represent the significance level provided

Confidence =0.9 or 9%

F test is a statistical test that uses a F Statistic to compare two population variances, with the sample deviations s1 and s2. The F statistic is always positive number since the variance it's always higher than 0. The statistic is given by:

F=\frac{s^2_2}{s^2_1}

Solution to the problem  

System of hypothesis

We want to test if the variation is equal for both groups or no, so the system of hypothesis are:

H0: \sigma^2_1 = \sigma^2_2

H1: \sigma^2_1 \neq \sigma^2_2

Calculate the statistic

Now we can calculate the statistic like this:

F=\frac{s^2_2}{s^2_1}=\frac{5.4}{2.3}=2.348

Now we can calculate the p value but first we need to calculate the degrees of freedom for the statistic. For the numerator we have n_2 -1 =16-1=15 and for the denominator we have n_1 -1 =16-1=15 and the F statistic have 15 degrees of freedom for the numerator and 15 for the denominator. And the P value is given by:

P value

Since is a bilateral test the p value is given by

p_v =2*P(F_{15,15}>2.348)=0.109

And we can use the following excel code to find the p value:"=2*(1-F.DIST(2.348,15,15,TRUE))"

Conclusion

Since the p_v > \alpha we have enough evidence to FAIL to reject the null hypothesis. And we can say that we don't have enough evidence to conclude that the variation is different between the two groups at 10% of significance.  

4 0
4 years ago
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