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Leto [7]
3 years ago
5

8th grade math help? I upvote :3

Mathematics
1 answer:
finlep [7]3 years ago
4 0
Hey! I said I'm here to help! :)
You might be interested in
Complete the square to write the quadratic expression in vertex form.
Anvisha [2.4K]

Answer:

1. (x - 3)² = 8

2. (x + 2)² = 3

3. (x + 6)² = $ \frac{101}{2} $

4. (x + 3)² = 27

5. (x + 4)² = 13

6.  $ \bigg( x - \frac{15}{9} \bigg) ^2 = \frac{261}{81} = \frac{29}{9} $

Step-by-step explanation:

Completion of Square: $ (x - a) ^2 = x^2 - 2ax + a^2 $

In the following problems the terms in the RHS of the above equation may be missing. We balance the equation. Simplify it and re write it in terms of LHS.

1. x² - 6x + 1 = 0

Taking the constant term to the other side, we get:

x² - 6x = - 1

⇒ x² - 2(3)x = -1

⇒ x² -2(3)x + 9 = - 1 + 9  [Adding 9 to both the sides]

⇒ x² -2(3)x + 3² = 8

⇒ (x - 3)² = 8 is the answer.

2. 3x² + 12x + 3 = 0

Note that the co-effecient of x² is not 1. We make it 1, by dividing the whole equation by 3. And then proceed like the previous problem.

3x² + 12x = -3

Dividing by 3 through out, x² + 4x = - 1

⇒ x² + 2(2) + 4 = -1 + 4

⇒ x² +2(2) + 2² = 3

⇒ (x + 2)² = 3 is the answer.

3. 2x² + 24x = 29

x² + 12x = $ \frac{29}{2} $

⇒ x² + 2(6)x + 36 = $ \frac{29}{2} $ + 36

⇒ x² + 2(6)x + 6² = $ \frac{29 + 72}{2} $

⇒ (x + 6)² = $ \frac{101}{2} $ is the answer.

4. x² + 6x - 18 = 0

x² + 6x = 18

⇒ x² + 2(3)x = 18

⇒ x² + 2(3)x + 9 = 18 + 9

⇒ x² + 2(3)x + 3² = 27

⇒ (x + 3)² = 27 is the answer.

5. x² + 8x + 3 = 0

x² + 8x = -3

⇒ x² + 2(4)x = -3

⇒ x² + 2(4)x + 16 = - 3 + 16

⇒ x² + 2(4)x + 16 = 13

⇒ (x + 4)² = 13 is the answer.

6. 9x² - 30x + 6 = 0

9x² - 30x = - 6

⇒ x² $ - \frac{30}{9} $ x = - 6

$ \implies x^2 -2 \bigg( \frac{15}{9} \bigg )x + \frac{225}{81} = - 6 + \frac{225}{81} $

$ \implies x^2 - 2\bigg( \frac{15}{9} \bigg ) x + \bigg ( \frac{15}{9} \bigg ) ^2 = \frac{261}{81} $

$ \bigg( x - \frac{15}{9} \bigg) ^2 = \frac{261}{81} = \frac{29}{9} $ is the answer.

6 0
3 years ago
Use the Pythagorean theorem to find the missing area
fgiga [73]

Answer:

28 cm^2

Step-by-step explanation:

a^+21^2=36^2

a^2+441=1225

a=28

5 0
3 years ago
I need help with this question
katrin [286]
I’m pretty sure it would be C
5 0
3 years ago
On a class trip to the museum,5/8 of the students saw the dinosaurs and 7/8 of the students saw either the jewelry collection or
inessss [21]

\frac{2}{8} of students only saw jewelry collection

<em><u>Solution:</u></em>

Given that, On a class trip to the museum,5/8 of the students saw the dinosaurs

7/8 of the students saw either the jewelry collection or the dinosaurs

<em><u>To find: Fraction of students only saw jewelry collection</u></em>

From given statement,

Fraction of students saw dinosaur = \frac{5}{8}

Fraction of students saw either the jewelry collection or the dinosaurs = \frac{7}{8}

Therefore,

Fraction of students only saw jewelry collection = Fraction of students saw either the jewelry collection or the dinosaurs - Fraction of students saw dinosaur

\rightarrow \frac{7}{8} - \frac{5}{8} = \frac{7-5}{8} = \frac{2}{8}

Thus \frac{2}{8} of students only saw jewelry collection

8 0
3 years ago
Suppose a lawn and garden company wants to determine the current percentage of customers who use fertilizer on their lawns. How
marishachu [46]

Answer:

n=601

Step-by-step explanation:

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".  

The margin of error is the range of values below and above the sample statistic in a confidence interval.  

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".  

The population proportion have the following distribution

p \sim N(p,\sqrt{\frac{\hat p(1-\hat p)}{n}})

In order to find the critical value we need to take in count that we are finding the interval for a proportion, so on this case we need to use the z distribution. Since our interval is at 95% of confidence, our significance level would be given by \alpha=1-0.95=0.05 and \alpha/2 =0.025. And the critical value would be given by:

z_{\alpha/2}=-1.96, z_{1-\alpha/2}=1.96

The confidence interval for the mean is given by the following formula:  

\hat p \pm z_{\alpha/2}\sqrt{\frac{\hat p (1-\hat p)}{n}}

The margin of error for the proportion interval is given by this formula:  

ME=z_{\alpha/2}\sqrt{\frac{\hat p (1-\hat p)}{n}}    (a)  

And on this case we have that ME =\pm 0.04 and we are interested in order to find the value of n, if we solve n from equation (a) we got:  

n=\frac{\hat p (1-\hat p)}{(\frac{ME}{z})^2}   (b)  

Since we don't have a prior estimation for the proportion we can use 0.5 as estimation. And replacing into equation (b) the values from part a we got:

n=\frac{0.5(1-0.5)}{(\frac{0.04}{1.96})^2}=600.25  

And rounded up we have that n=601

3 0
3 years ago
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