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3 years ago

Help please!! i don’t understand this one!

Mathematics

1 answer:

12345 [234]3 years ago

5 0

Answer:

C, D

Step-by-step explanation:

This equation can be solved any of several ways. One that doesn't require much thought is using the quadratic formula.

For ax² +bx +c = 0, the solutions are ...

$x=\dfrac{-b\pm\sqrt{b^2-4ac}}{2a}$

In the given equation, a=2, b=11, c=5, so this becomes ...

$x=\dfrac{-11\pm\sqrt{11^2-4\cdot2\cdot5}}{2\cdot2}=\dfrac{-11\pm\sqrt{81}}{4}\\\\x=\dfrac{-11\pm9}{4}=\left\{-\dfrac{20}{4},-\dfrac{2}{4}\right\}=\{-5,-\frac{1}{2}\}$

The solutions are ...

C. x = -5

D. x = -1/2

_____

My personal favorite is using a graphing calculator. The solutions are the x-intercepts of the expression on the left. That is, where its value is zero, as the equation says.

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A population of 60 rabbits increases by 25% each year for 8 years. Find the population the end of each year

MrRa [10]

Answer & Step-by-step explanation:

It increased by 10 each year

Year 1 of 8: 70

Year 2 of 8: 80

Year 3 of 8: 90

Year 4 of 8: 100

Year 5 of 8: 110

Year 6 of 8: 120

Year 7 of 8: 130

Year 8 of 8 (Final Year): 140

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Hope this helps!!! :)

3 0

3 years ago

Read 2 more answers

What is 18-0.9 if you know answer pls lol

Harlamova29_29 [7]

Answer:

17.1

Step-by-step explanation:

3 0

3 years ago

Keenan scored 80 points on an exam that had a mean score of 77 points and a standard deviation of 4.9 points. Rachel scored 78 p

Artemon [7]

Answer:

Keenan's z-score was of 0.61.

Rachel's z-score was of 0.81.

Step-by-step explanation:

Z-score:

Problems of normal distributions can be solved using the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the z-score 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 p-value, we get the probability that the value of the measure is greater than X.

Keenan scored 80 points on an exam that had a mean score of 77 points and a standard deviation of 4.9 points.

This means that $X = 80, \mu = 77, \sigma = 4.9$

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

$Z = \frac{80 - 77}{4.9}$

$Z = 0.61$

Keenan's z-score was of 0.61.

Rachel scored 78 points on an exam that had a mean score of 75 points and a standard deviation of 3.7 points.

This means that $X = 78, \mu = 75, \sigma = 3.7$ . So

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

$Z = \frac{75 - 78}{3.7}$

$Z = 0.81$

Rachel's z-score was of 0.81.

6 0

3 years ago

20% of the total candy in a basket is Reese's chocolate. There are 8 Reese's in the basket. What is the total number of pieces o

Likurg_2 [28]

Answer:

I believe it is 40. I'm not 100% sure though

Step-by-step explanation:

If 20% of the candy is reese's and there are 8 reese's in the basket, to find the answer you must multiply 8 by 5. You multiply 8 by 5 because to get 100% you have to multiply 20% by 5 to get 100%.

6 0

3 years ago

X² + y² = 34 x + y =8

Nataly [62]

Step-by-step explanation:

${x}^{2} + {y}^{2} = 34 \\ x + y = 8 \\ x = 8 - y \\ substitute \: x \: in \\ {x}^{2} + {y}^{2} = 34 \\ {(8 - 4)}^{2} + {y}^{2} = 34 \\ {(8 - 4) }^{2} = {y}^{2} - 16y + 64 \\ {y}^{2} - 16y + 64 + {y}^{2} = 34 \\ {2y}^{2} - 16y + 64 = 34 \\ {2y}^{2} - 16y + 64 - 34 = 0 \\ {2y}^{2} - 16y + 30 = 0 \\ 2 {y}^{2} - 6y - 10y + 30 = 0 \\ (2 {y}^{2} - 6y) - (10y + 30) = 0 \\ 2y(y - 3) - 10(y - 3) = 0 \\ (2y - 10)(y - 3) \\ 2y = 10 \\ y = \frac{10}{2} \\ y = 5 \\ or \\ y = 3 \\ if \: y = 5 \: \: x = 3 \\ if \: y = 3 \: \: x = 5$

4 0

3 years ago