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3 years ago

3x^2-12x-21=0 solve by completing the square

Mathematics

1 answer:

morpeh [17]3 years ago

3 0

Answer:

x = 2 ± √11 (I believe)

Step-by-step explanation:

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-12 + 18. = 70 complete the square

FromTheMoon [43]

-12 + 18 = 70 - 64 or(-12+18)+(6*12)-2

8 0

2 years ago

Evelyn has dance class every Saturday. It lasts 1 hour and 40 minutes and is over at 12:45 P.M.

leva [86]

Answer:

Evelyn's dance class on Saturday starts at 11:05 A.M.

Step-by-step explanation:

I know this because if her class takes an hour and 40 minutes you would subtract the hour and 40 minutes from 12:45 so you could do 12 - 1 which equals 11. Then you would do 45 - 40 which equals 5. And last you would put the new times together so it would be, 11:05. Her dance class starts at 11:05 A.M.

7 0

3 years ago

⦁ In a simple random sample of 1219 US adults, 354 said that their favorite sport to watch is football. Construct a 95% confiden

fomenos

Answer:

95% confidence interval for the proportion of adults in the United States whose favorite sport to watch is football is [0.265 , 0.316].

Step-by-step explanation:

We are given that in a simple random sample of 1219 US adults, 354 said that their favorite sport to watch is football.

Firstly, the pivotal quantity for 95% confidence interval for the proportion of adults in the United States whose favorite sport to watch is football is given by;

P.Q. = $\frac{\hat p-p}{\sqrt{\frac{\hat p(1-\hat p)}{n} } }$ ~ N(0,1)

where, $\hat p$ = proportion of adults in the United States whose favorite sport to watch is football in a sample of 1219 adults = $\frac{354}{1219}$

n = sample of US adults = 1291

p = population proportion of adults

Here for constructing 95% confidence interval we have used One-sample z proportion statistics.

So, 95% confidence interval for the population proportion, p is ;

P(-1.96 < N(0,1) < 1.96) = 0.95 {As the critical value of z at 2.5%

significance level are -1.96 & 1.96}

P(-1.96 < $\frac{\hat p-p}{\sqrt{\frac{\hat p(1-\hat p)}{n} } }$ < 1.96) = 0.95

P( $-1.96 \times {\sqrt{\frac{\hat p(1-\hat p)}{n} }$ < ${\hat p-p}$ < $1.96 \times {\sqrt{\frac{\hat p(1-\hat p)}{n} }$ ) = 0.95

P( $\hat p-1.96 \times {\sqrt{\frac{\hat p(1-\hat p)}{n} }$ < p < $\hat p+1.96 \times {\sqrt{\frac{\hat p(1-\hat p)}{n} }$ ) = 0.95

95% confidence interval for p = [ $\hat p-1.96 \times {\sqrt{\frac{\hat p(1-\hat p)}{n} }$ , $\hat p+1.96 \times {\sqrt{\frac{\hat p(1-\hat p)}{n} }$ ]

= [ $\frac{354}{1219}-1.96 \times {\sqrt{\frac{\frac{354}{1219}(1-\frac{354}{1219})}{1219} }$ , $\frac{354}{1219}+1.96 \times {\sqrt{\frac{\frac{354}{1219}(1-\frac{354}{1219})}{1219} }$ ]

= [0.265 , 0.316]

Therefore, 95% confidence interval for the proportion of adults in the United States whose favorite sport to watch is football is [0.265 , 0.316].

5 0

3 years ago

What is an estimate for 17 divided by 1569

Y_Kistochka [10]

It will be 93 because it 92 but you have to round up with deimal number

5 0

3 years ago

Read 2 more answers

If each side of a square grows 6 mm, the area of the square is multiplied by 16. How long are the sides of the original square

Phoenix [80]

Answer:

2 mm

Step-by-step explanation:

Let x be the sides of the original square,

then the area of the original square is x^2

The sides of the new square is x + 6

The area is (x + 6)^2

Then (x + 6)^2 = 16*x^2

Take square root on both sides and get

x + 6 = 4x,

3x = 6

so x = 2 mm

3 0

2 years ago