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3 years ago

Factor the polynomial below. 9x^2-1 A. (-1)(9x-1) B. (3x-1)(3x-1) C. (3x-1)(3x+1) D. (x-1)(9x+1)

Mathematics

1 answer:

telo118 [61]3 years ago

6 0

Answer:

(3x-1) (3x+1)

Step-by-step explanation:

9x^2-1

Rewriting as

(3x)^2 - 1^2

This is the difference of squares

a^2 - b^2 = (a-b)(a+b)

(3x-1) (3x+1)

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A=a-b/5+c solve for a

n200080 [17]

Answer:

A= my

Step-by-step explanation:

8 0

3 years ago

I need help with #39-42, please explain.

shusha [124]

For question 39 & 40, we need to use the below equation to complete the sentence

$l=m\sqrt{n}$

Question 39:

When ' n ' increase, the $\sqrt{n}$ will also increase and that multiplied with constant ' m ', the l will also increase.

Solution for question 39:

As $n$ increases and $m$ stays constant , $l$ increases

-------

Question 40:

Solving the equation for m, we get

$l = m\sqrt{n} \\ \\ m=\frac{l}{\sqrt{n}}$

When ' l ' increases, the numerator increase, the denominator stays constant because 'n' stays constant, for this condition, the fraction increases.

Solution for question 40:

As $l$ increase and $n$ stays constant, $m$ increases

------

For question 41 & 42, we need to use the below equation to complete the sentence

$r=s^2/t^2$

Question 41:

When $s$ is triped, the equation will be...

$r=(3s)^2/t^2=\frac{3^{2}s^{2}}{t^2} =9s^2/t^2$

Solution for question 41:

If $s$ is tripled and $t$ stays constant, $r$ is multiplied by 9

--------

Question 42:

When t is doubled, the equation will be...

$r=s^2/(2t)^2=\frac{s^2}{2^2 \cdot t^2}=\frac{s^2}{4t^2}\\ \\ r=0.25s^2/t^2 \; \; (or) \; \; \frac{1}{4} \cdot \frac{s^2}{t^2}$

Solution for 42:

If $t$ doubled and $s$ stays constant, $r$ is multiplied by 1/4 or 0.25

3 0

3 years ago

WILL GIVE BRAINLIEST IF CORRECT!!

vfiekz [6]

Answer:

$\displaystyle y=-0.927x+13.63$

Step-by-step explanation:

Simple Linear Regression

It a function that represents the relationship between two or more variables in a given data set. It uses the method of the least-squares regression line which minimizes the error between the estimate function and the real data.

Let's compute the best-fit line for the data

$x=\{1,5,6,12,15\}$

$y=\{14,11,4,2,1\}$

First, we find the sums

$\displaystyle \sum x=1+5+6+12+15=39$

$\displaystyle \sum y=14+11+4+2+1=32$

Then, we compute the averages values

$\displaystyle \bar{x}=\frac{39}{5}=7.8$

$\displaystyle \bar{y}=\frac{32}{5}=6.4$

We will also compute the sums of the cross-products and the sum of the squares

$\displaystyle \sum xy=(1)(14)+(5)(11)+(6)(4)+(12)(2)+(15)(1)=137$

$\displaystyle \sum x^2=1^2+5^2+6^2+12^2+15^2=1+25+36+144+225$

$\displaystyle \sum x^2=431$

We will compute Sxy and Sxx

$\displaystyle S_{xy}=\sum xy-\frac{\sum x\ \sum y}{n}$

$\displaystyle S_{xy}=137-\frac{(39)(32)}{5}$

$\displaystyle S_{xy}=-117.6$

$\displaystyle S_{xx}=\sum x^2-\frac{(\sum x)^2}{n}$

$\displaystyle S_{xx}=431-\frac{39}{5}^2=126.8$

The slope of the linear regression function is given by

$\displaystyle m=\frac{S_{xy}}{S_{xx}}=\frac{-117.6}{126.8}=-0.927$

The y-intercept ot the linear function is

$\displaystyle b=\bar{y}-b\bar{x}=6.4-(-0.927)(7.8)$

$\displaystyle b=13.63$

Thus the best-fit line is

$\displaystyle y=-0.927x+13.63$

The correct option is the last one

5 0

3 years ago

A sandbox has a volume of 648 cubic feet. what is the volume, in cubic yards, of the sandbox?

Eduardwww [97]

We know that

1 cubic yards equals to--------------> 27 cubic feet
then
I apply a rule of three
if 1 cubic yards ------------------- 27 ft³
X----------------------------------> 648 ft³
X=648/27=24 cubic yards

the answer is 24 cubic yards

6 0

3 years ago

If (3-4i) (x+iy) = 3 root 5 show that x^2 + y^2=9/5

NNADVOKAT [17]

Answer:

the answer is 2 + i.

Step-by-step explanation:

Let the square root of 3 + 4i be x + iy.

So (x + iy) (x +iy) = 3 +4i

=> x^2 + xyi + xyi + i^2*y^2 = 3 + 4i

=> x^2 – y^2 + 2xyi = 3 + 4i

Equate the real and complex terms

=> x^2 - y^2 = 3 and 2xy = 4

2xy = 4

=> xy = 2

=> x = 2/y

Substitute in

=> x^2 - y^2 = 3

=> 4/y^2 - y^2 = 3

=> 4 – y^4 = 3y^2

=> y^4 + 3y^2 – 4 = 0

=> y^4 + 4y^2 – y^2 – 4 =0

=> y^2(y^2 + 4) – 1(y^2 + 4) =0

=> (y^2 – 1) (y^2 + 4) =0

Therefore y^2 = 1, we ignore y^2 = -4 as it gives complex values of y.

Therefore y = 1 and x = 2/1 = 2

The required square root of 3 + 4i is 2 + i.

5 0

3 years ago