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3 years ago

Solve by the substitution method. 6x + 8y = 0 -7x + y = 31

Mathematics

1 answer:

jekas [21]3 years ago

7 0

Answer:

(-4, 3)

General Formulas and Concepts:

Pre-Algebra

Order of Operations: BPEMDAS

Brackets
Parenthesis
Exponents
Multiplication
Division
Addition
Subtraction

Left to Right

Equality Properties

Algebra I

Solving systems of equations using substitution/elimination

Step-by-step explanation:

Step 1: Define Systems

6x + 8y = 0

-7x + y = 31

Step 2: Rewrite Systems

-7x + y = 31

Add 7x to both sides: y = 7x + 31

Step 3: Redefine Systems

6x + 8y = 0

y = 7x + 31

Step 4: Solve for x

Substitution

Substitute in y: 6x + 8(7x + 31) = 0
Distribute 8: 6x + 56x + 248 = 0
Combine like terms: 62x + 248 = 0
Isolate x term: 62x = -248
Isolate x: x = -4

Step 4: Solve for y

Define equation: -7x + y = 31
Substitute in x: -7(-4) + y = 31
Multiply: 28 + y = 31
Isolate y: y = 3

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Gekata [30.6K]

Answer:

d. y-intercept (0,5); x-intercept (5/2,0)

Step-by-step explanation:

y intercept is when x = 0, then y = 5 or (0,5)

x intercept is when y = 0, then x = 5/2 or (5/2,0)

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2 years ago

If g || h and m∠2 = 110 what is m∠6\

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4 years ago

Hi can you help with some ratio and proportion questions

pochemuha

Answer:

1a. 12 : 40

1b. 15 : 21

1c. 24 : 44

1d. 2 : 25

2. 40 boys and 100 girls

3. 96 girls

4. £71.43

5a. 9 : 4

5b. 3 : 1

5c. 3 : 5

6. 210 : 90

7. Sorry, I couldn't figure out how to solve this question :(

Step-by-step explanation:

Since I'll be using a similar method to solve these questions, I won't go into a detailed explanation for how I solved every single question. If you do need extra help, please ask in the comments below my answer.

1. Let's use part (a) as an example. The ratio is 3:10. To new ratio is ?:40. So, 10 becomes 40. What number multiplied by 10 equals 40? The answer is 4. If 10 is multiplied by 4, then 3 must be multiplied by 4 as well. 3*4 = 12, so the ratio is 12:40.

In part b the ratio is multiplied by 3, part c is 4, and part d is 1/2.

2. To solve this, add the values on both sides of the ratio together: 2 + 5 = 7. Now, divide the total number of pupils, 140, by 7: 140/7 = 20. Finally, multiply 20 by both sides of the ratio: 2 * 20:5 * 20 = 40:100. There are 40 boys and 100 girls.

3. To solve this I used the same method as the one I used in question 1.

4. The ratio is 5:140, where 140 becomes 2000. To solve, use the method used in question 1.

5. Simplifying ratios is the same as simplifying fractions. Find the greatest common factor of the values on both sides of the ratio and divide both sides by that factor. For example, in part a the factor for 45:20 is 5. 45/5 = 9 and 20/5 = 4. The ratio becomes 9:4.

For part b the factor is 9 and for part c the factor is 50.

6. Same method as was used in question 2.

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3 years ago

Tain has a great literary tradition that spans centuries. One might assume, then, that Britons read more than citizens of other

tresset_1 [31]

Answer:

Null hypothesis: $p_{1} \leq p_{2}$

Alternative hypothesis: $p_{1} > p_{2}$

$z=3.02$

$p_v =P(Z>3.02)=0.00127$

The p value is a very low value and using any significance level for example $\alpha=0.05, 0,1,0.15$ always $p_v$ so we can conclude that we have enough evidence to reject the null hypothesis, and we can say the the proportion of Canadians is not significantly higher than the porportions of readers at Britons.

Step-by-step explanation:

1) Data given and notation

$X_{1}=0.86*1004$ represent the number of Canadians randomly sampled by Gallup that read at least one book in the past year

$X_{2}=0.81*1009$ represent the number of Britons randomly sampled that read at least one book in the past year

$n_{1}=1004$ sample of Gallup selected

$n_{2}=1009$ sample of Britons selected

$p_{1}=0.86$ represent the proportion of Canadians randomly sampled by Gallup that read at least one book in the past year

$p_{2}=0.81$ represent the proportion of Britons randomly sampled that read at least one book in the past year

z would represent the statistic (variable of interest)

$p_v$ represent the value for the test (variable of interest)

2) Concepts and formulas to use

We need to conduct a hypothesis in order to check if the proportion for men with red/green color blindness is a higher than the rate for women , the system of hypothesis would be:

Null hypothesis: $p_{1} \leq p_{2}$

Alternative hypothesis: $p_{1} > p_{2}$

We need to apply a z test to compare proportions, and the statistic is given by:

$z=\frac{p_{1}-p_{2}}{\sqrt{\hat p (1-\hat p)(\frac{1}{n_{1}}+\frac{1}{n_{2}})}}$ (1)

Where $\hat p=\frac{X_{1}+X_{2}}{n_{1}+n_{2}}=\frac{0.81+0.86}{2}=0.835$

3) Calculate the statistic

Replacing in formula (1) the values obtained we got this:

$z=\frac{0.86-0.81}{\sqrt{0.835(1-0.835)(\frac{1}{1004}+\frac{1}{1009})}}=3.02$

4) Statistical decision

For this case we don't have a significance level provided $\alpha$ , but we can calculate the p value for this test.

Since is a one side test the p value would be:

$p_v =P(Z>3.02)=0.00127$

So the p value is a very low value and using any significance level for example $\alpha=0.05, 0,1,0.15$ always $p_v$ so we can conclude that we have enough evidence to reject the null hypothesis, and we can say the the proportion of Canadians is not significantly higher than the porportions of readers at Britons.

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4 years ago

sophia is 6 years older than her brother eric. the sum of their ages is 28. write and solve an equation to find sophia and Eric'

zimovet [89]

s = 6 + e

s + e = 28

We can use this system of equations to find the exact values of s and e.

We have a current value of s, so we can find the exact value of e now.

e + e + 6 = 28

Combine like terms.

2e + 6 = 28

Subtract both sides by 6.

2e = 22

Divide both sides by 2.

e = 11

Now we have an exact value of e, and can solve for the value of s.

s = 6 + 11

s = 17

Sophia is 17 years old, and Eric is 11 years old.

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3 years ago