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2 years ago

What are the solutions to x2 – 10x = 39?

Mathematics

1 answer:

oee [108]2 years ago

7 0

Answer: x=−3 or x=13

Step-by-step explanation:

Step 1: Subtract 39 from both sides.

x2−10x−39=39−39

x2−10x−39=0

Step 2: Factor left side of equation.

(x+3)(x−13)=0

Step 3: Set factors equal to 0.

x+3=0 or x−13=0

x=−3 or x=13

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Round to the nearest hundredth (2 decimal places) when necessary

shusha [124]

Answer:

volume = 91 cm²

perimeter = 41.1 in

Step-by-step explanation:

volume = 1/2(b1+b2)(h) = 1/2(11 + 15)(7) = 91 cm²

8 0

2 years ago

Alexa pays 7/20 of a dollar for each minute she uses her pay-as-you-go phone for a call, and 2/5 of a dollar for each minute of

9966 [12]

Answer:

The system of equations is x + y = 85 and 7/20x+2/5y=31
To eliminate the x-variable from the equations, you can multiply the equation with the fractions by 20 and multiply the other equation by -7.
B-She used 60 minutes for calling and 25 minutes for data.

Step-by-step explanation:

It is always a good idea to start by defining variables in such a problem. Here, we can let x represent the number of calling minutes, and y represent the number of data minutes. The the total number of minutes used is ...

x + y = 85

The total of charges is the sum of the products of charge per minute and minutes used:

7/20x + 2/5y = 31.00

We can eliminate the x-variable in these equations by multiplying the first by -7 and the second by 20, then adding the result.

-7(x +y) +20(7/20x +2/5y) = -7(85) +20(31)

-7x -7y +7x +8y = -595 +620 . . . . eliminate parentheses

y = 25 . . . . . . . . simplify

Then the value of x is

x = 85 -y = 85 -25

x = 60

7 0

3 years ago

Read 2 more answers

Help please! Thank you

Anna71 [15]

First thing to do is set up your equation:
45/x = 20/100
Cross multiply
4500 = 20x
And divide by 20

Answer: 225 people were surveyed

6 0

2 years ago

Read 2 more answers

Convertir 675 Faren a Kelvin (Con ecuaciones porfavor)

alexandr1967 [171]

Answer:

<em>(675°F − 32) × 5/9 + 273.15 = 630.372K </em>

Hope it's right if not so sorry :)

5 0

2 years ago

Refer to the following scenario:You want to see if there is a difference between the exercise habits of Science majors and Math

bekas [8.4K]

Answer:

1. H0: P1 = P2

2. Ha: P1 ≠ P2

3. pooled proportion p = 0.542

4. P-value = 0.0171

5. The null hypothesis failed to be rejected.

At a signficance level of 0.01, there is not enough evidence to support the claim that there is significant difference between the exercise habits of Science majors and Math majors .

6. The 99% confidence interval for the difference between proportions is (-0.012, 0.335).

Step-by-step explanation:

We should perform a hypothesis test on the difference of proportions.

As we want to test if there is significant difference, the hypothesis are:

Null hypothesis: there is no significant difference between the proportions (p1-p2 = 0).

Alternative hypothesis: there is significant difference between the proportions (p1-p2 ≠ 0).

The sample 1 (science), of size n1=135 has a proportion of p1=0.607.

$p_1=X_1/n_1=82/135=0.607$

The sample 2 (math), of size n2=92 has a proportion of p2=0.446.

$p_2=X_2/n_2=41/92=0.446$

The difference between proportions is (p1-p2)=0.162.

$p_d=p_1-p_2=0.607-0.446=0.162$

The pooled proportion, needed to calculate the standard error, is:

$p=\dfrac{X_1+X_2}{n_1+n_2}=\dfrac{82+41}{135+92}=\dfrac{123}{227}=0.542$

The estimated standard error of the difference between means is computed using the formula:

$s_{p1-p2}=\sqrt{\dfrac{p(1-p)}{n_1}+\dfrac{p(1-p)}{n_2}}=\sqrt{\dfrac{0.542*0.458}{135}+\dfrac{0.542*0.458}{92}}\\\\\\s_{p1-p2}=\sqrt{0.001839+0.002698}=\sqrt{0.004537}=0.067$

Then, we can calculate the z-statistic as:

$z=\dfrac{p_d-(\pi_1-\pi_2)}{s_{p1-p2}}=\dfrac{0.162-0}{0.067}=\dfrac{0.162}{0.067}=2.4014$

This test is a two-tailed test, so the P-value for this test is calculated as (using a z-table):

$\text{P-value}=2\cdot P(z>2.4014)=0.0171$

As the P-value (0.0171) is bigger than the significance level (0.01), the effect is not significant.

The null hypothesis failed to be rejected.

At a signficance level of 0.01, there is not enough evidence to support the claim that there is significant difference between the exercise habits of Science majors and Math majors .

We want to calculate the bounds of a 99% confidence interval of the difference between proportions.

For a 99% CI, the critical value for z is z=2.576.

The margin of error is:

$MOE=z \cdot s_{p1-p2}=2.576\cdot 0.067=0.1735$

Then, the lower and upper bounds of the confidence interval are:

$LL=(p_1-p_2)-z\cdot s_{p1-p2} = 0.162-0.1735=-0.012\\\\UL=(p_1-p_2)+z\cdot s_{p1-p2}= 0.162+0.1735=0.335$

The 99% confidence interval for the difference between proportions is (-0.012, 0.335).

6 0

3 years ago