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Delicious77 [7]
2 years ago
12

How do you rewrite an equation by completing the square? x^2+10x+21=0

Mathematics
1 answer:
AleksAgata [21]2 years ago
7 0

Answer:

Step-by-step explanation:

x²+10x+21=0

x²+10x+(10/2)²-(10/2)²+21=0

x²+10x+25-25+21=0

(x+5)²-4=0

(x+5)²=4

(x+y)²=(x+y)(x+y)=x(x+y)+y(x+y)=x²+xy+xy+y²=x²+2xy+y²

(x+y)²=x²+2xy+y²

coefficient of x=2y

y²=[(coefficient of x)/2]²=(2y/2)²=y²

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Write a rule for solving equations like 2x=24 without using model. Use a related division sentence to explain your answer.
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The equation for a parabola has the form y = ax2 + bx + c, where a, b, and c are constants and a ≠ 0. find an equation for the p
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To solve the problem, substitute the given points for x in the given equation to get

-10=(-1)^2a+(-1)b+c\Rightarrow-10=a-b+c \\ -6=(1)^2a+(1)b+c\Rightarrow-6=a+b+c \\ -13=(2)^2a+(2)b+c\Rightarrow-13=4a+2b+c

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5 0
3 years ago
Read 2 more answers
The distribution of weekly salaries at a large company is right skewed with a mean of $1000 and a standard deviation of $350. Wh
Shtirlitz [24]

Answer:

68.76% probability that the sampling error made in estimating the mean weekly salary for all employees of the company by the mean of a random sample of weekly salaries of 50 employees will be at most $50

Step-by-step explanation:

To solve this question, we have to understand the normal probability distribution and the central limit theorem.

Normal probability distribution:

Problems of normally distributed samples are solved using the z-score formula.

In a set with mean \mu and standard deviation \sigma, the zscore of a measure X is given by:

Z = \frac{X - \mu}{\sigma}

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

Central limit theorem:

The Central Limit Theorem estabilishes that, for a random variable X, with mean \mu and standard deviation \sigma, a large sample size can be approximated to a normal distribution with mean \mu and standard deviation, which is also called standard error s = \frac{\sigma}{\sqrt{n}}

In this problem, we have that:

\mu = 1000, \sigma = 350, n = 50, s = \frac{350}{\sqrt{50}} = 49.5

What is the probability that the sampling error made in estimating the mean weekly salary for all employees of the company by the mean of a random sample of weekly salaries of 50 employees will be at most $50

This is the pvalue of Z when X = 1000+50 = 1050 subtracted by the pvalue of Z when X = 1000-50 = 950. So

X = 1050

Z = \frac{X - \mu}{\sigma}

By the Central Limit Theorem

Z = \frac{X - \mu}{s}

Z = \frac{1050-1000}{49.5}

Z = 1.01

Z = 1.01 has a pvalue of 0.8438

X = 950

Z = \frac{X - \mu}{s}

Z = \frac{950-1000}{49.5}

Z = -1.01

Z = -1.01 has a pvalue of 0.1562

0.8438 - 0.1562 = 0.6876

68.76% probability that the sampling error made in estimating the mean weekly salary for all employees of the company by the mean of a random sample of weekly salaries of 50 employees will be at most $50

4 0
2 years ago
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