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3 years ago

2x^2-28=10x Factor then solve?

Mathematics

2 answers:

maria [59]3 years ago

4 0

2x^2-28=10x

x^2-14=5x

x^2-5x-14=0

(x-7)(x+2)=0

x = 7, -2

seraphim [82]3 years ago

4 0

Answer: Yeah. Factor by grouping because it’s the easiest.

Step-by-step explanation:

2x^2-28=10x

-10x -10x

______________

2x^2-10x-28 = 0

_______________

(2x^2+4x)(-14x-28)=0

You subtract the 10x from both sides and get 2x^2-10x-28 = 0. Then you group. Two parentheses have to be made. Put the 2x^2 in one and the -38 in the other. Multiply the 2 (leading coefficient) by the -28 and get -56. You need two numbers that multiply to -56 but add to -10. Those numbers are -14 and 4. So it’s (2x^2+4x)(-14x-28)=0. Then you just solve. Sorry bout the wordy-ness.

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A survey was taken of students in math classes to find out how many hours per day students spend

Hoochie [10]

Answer:

1. Mean, because there are no outliers that affect the center

Step-by-step explanation:

Second period: 3,2,3,1,3, 4, 2, 4, 3, 1, 0, 2, 3, 1, 2

Sorted values : 0, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 4, 4

The mean = ΣX / n

n = sample size, n = 15

Mean = 34 / 15 = 2.666

The median = 1/2(n+1)th term.

1/2(16)th term = 8th term.

The 8th term = 2

The best measure of centre is the mean because the values for the second period has no outliers that might have affected the centre of the distribution.

Both interquartile range and standard deviation are measures of spread and not measures of centre.

6 0

3 years ago

30 tens - 3 tens 3 tenths

lubasha [3.4K]

300-30.3=269.7 because you barrow from 3 in 300 because you can't round into 0 and that equalled 7 and than you do 9-0=9 and there's 009.7 than you do 9-3=6 and that's 069.7 and you do 2-0=2 and there's 269.7

4 0

3 years ago

Which expression is equivalent to 5y^3/(5y)^-2

Serggg [28]

Answer:

5^3 y^5

125 y^5

Step-by-step explanation:

5y^3/(5y)^-2

Distribute the exponent in the denominator

5y^3/(5 ^-2 y^-2)

A negative exponent in the denominator brings it to the numerator

5y^3 5 ^2 y^2

Combine like terms

5 * 5^2 * y^3 5^2

We know that a^b * a^c = a^(b+c)

5^(1+2) * y^( 3+2)

5^3 y^5

125 y^5

6 0

3 years ago

The time it takes for a planet to complete its orbit around a particular star is called the? planet's sidereal year. The siderea

BartSMP [9]

Answer:

(a) See below

(b) r = 0.9879

(d) See below

(e) No.

Step-by-step explanation:

(a) Plot the data

I used Excel to plot your data and got the graph in Fig 1 below.

(b) Correlation coefficient

One formula for the correlation coefficient is

$r = \dfrac{\sum{xy} - \sum{x} \sum{y}}{\sqrt{\left [n\sum{x}^{2}-\left (\sum{x}\right )^{2}\right]\left [n\sum{y}^{2} -\left (\sum{y}\right )^{2}\right]}}$

The calculation is not difficult, but it is tedious.

(i) Calculate the intermediate numbers

We can display them in a table.

x y xy x² y²

36 0.22 7.92 1296 0.05

67 0.62 42.21 4489 0.40

93 1.00 93.00 20164 3.46

433 11.8 5699.4 233289 139.24

887 29.3 25989.1 786769 858.49

1785 82.0 146370 3186225 6724

2797 163.0 455911 7823209 26569

3675 248.0 911400 13505625 61504

9965 537.81 1545776.75 25569715 95799.63

(ii) Calculate the correlation coefficient

$r = \dfrac{\sum{xy} - \sum{x} \sum{y}}{\sqrt{\left [n\sum{x}^{2}-\left (\sum{x}\right )^{2}\right]\left [n\sum{y}^{2} -\left (\sum{y}\right )^{2}\right]}}\\\\= \dfrac{9\times 1545776.75 - 9965\times 537.81}{\sqrt{[9\times 25569715 -9965^{2}][9\times 95799.63 - 537.81^{2}]}} \approx \mathbf{0.9879}$

(c) Regression line

The equation for the regression line is

y = a + bx where

$a = \dfrac{\sum y \sum x^{2} - \sum x \sum xy}{n\sum x^{2}- \left (\sum x\right )^{2}}\\\\= \dfrac{537.81\times 25569715 - 9965 \times 1545776.75}{9\times 25569715 - 9965^{2}} \approx \mathbf{-12.629}\\\\b = \dfrac{n \sum xy - \sum x \sum y}{n\sum x^{2}- \left (\sum x\right )^{2}} - \dfrac{9\times 1545776.75 - 9965 \times 537.81}{9\times 25569715 - 9965^{2}} \approx\mathbf{0.0654}\\\\\\\text{The equation for the regression line is $\large \boxed{\mathbf{y = -12.629 + 0.0654x}}$}$

(d) Residuals

Insert the values of x into the regression equation to get the estimated values of y.

Then take the difference between the actual and estimated values to get the residuals.

x y Estimated Residual

36 0.22 -10 10

67 0.62 -8 9

93 1.00 -7 8

142 1.86 -3 5

433 11.8 19 - 7

887 29.3 45 -16

1785 82.0 104 -22

2797 163.0 170 - 7

3675 248.0 228 20

(e) Suitability of regression line

A linear model would have the residuals scattered randomly above and below a horizontal line.

Instead, they appear to lie along a parabola (Fig. 2).

This suggests that linear regression is not a good model for the data.

4 0

3 years ago

Numbers greater than 20 that have 9 as a factor

riadik2000 [5.3K]

80 has 9 factor because 1×80=80. 2×40-80. 4×20=80. 5×16=80. 8×10=80 . 10 ×8=80. 20×4=80. 40×2=80. and 80×1=80 80 is greater than 20 and that has 9 factors

4 0

3 years ago