Find the exact value tan^-1(tan(3pi))

8. The sum of two numbers is 8 less than twice the first number. Their difference is 4 less than twice

Delicious77 [7]

Answer:

14 and 6

Step-by-step explanation:

Let's start by naming the first number x.

We can name the second number y.

We can set up equations to model our situation.

x+y=2x-8

x-y=2y-4

Let's simplify the equations.

x+y=2x-8

Subtract 2x from both sides

-x+y=-8

__________

x-y=2y-4

Subtract 2y from both sides.

x-3y=-4

Add the two equations together to eliminate x.

x-3y=-4

-x+y=-8

________

0x-2y=-12

-2y=-12

Divide both sides by -2.

y=6

The second number is 6.

Plug that back in.

x+6=2x-8

Subtract x from both sides

6=x-8

Add 8 to both sides

x=14

The first number is 14

7 0

3 years ago

What is 28- 12.5% decrease???

OLEGan [10]

Ok so I assume
28 and decreased by 12.5%

percent means partst out of 100 so
12.5%=12.5/100=0.125
first find 12.5% of 28 then subtract
0.125 times 28=3.5
decrease
28-3.5=24.5

answer is 24.5

3 0

3 years ago

What is the value of x and the length of segment DE?

Mandarinka [93]

Answer:

Part 1) $x=6.6\ units$

Part 2) $DE=16.2\ units$

Step-by-step explanation:

Part 1) Find the value of x

we know that

Triangles CDF and FDE are similar

therefore

The ratio of its corresponding sides is proportional and its corresponding angles are congruent

so

$CD/FD=FD/DE$

$\frac{5}{9}=\frac{9}{2x+3} \\ \\5*(2x+3)=9*9\\ \\10x+15=81\\ \\10x= 81-15\\ \\10x=66\\ \\ x=6.6\ units$

Part 2) Find the length of DE

$DE=2x+3$

substitute the value of x

$DE=2(6.6)+3=16.2\ units$

8 0

2 years ago

Read 2 more answers

Rewrite the equation x = 65 - 60p by factoring the side that contains the variable p.

grigory [225]

Answer: $x=5(13-12p)$

Step-by-step explanation:

Given equation: $x=65-60p$

$\\\Rightarrowx=(5\times13)-(5\times12)p$

Since 5 is the greatest common factor of 65 and 60 in the given expression.

Therefore, the above expression can be written as

$x=5(13-12p)$

Hence, by factoring the side that contains the variable p we have the expression $x=5(13-12p)$ .

7 0

3 years ago

The least-squares regression model y =−3.4+5.2x and correlation coefficient r=−0.66 were calculated for a set of bivariate data

Makovka662 [10]

Answer:

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

For this case the value of r = -0.66

Now we can calculate the determination coeffcient:

$r^2 = (-0.66)^2 = 0.4356$

And then we can conclude that 43.56% of the variation in y can be explained by the explanatory variable

And then 100-43.56 = 56.44 % of the variation in y that cannot be explained by the explanatory variable

Step-by-step explanation:

For this case we need to calculate the slope with the following formula:

$m=\frac{S_{xy}}{S_{xx}}$

Where:

$S_{xy}=\sum_{i=1}^n x_i y_i -\frac{(\sum_{i=1}^n x_i)(\sum_{i=1}^n y_i)}{n}$

$S_{xx}=\sum_{i=1}^n x^2_i -\frac{(\sum_{i=1}^n x_i)^2}{n}$

$\bar x= \frac{\sum x_i}{n}$

$\bar y= \frac{\sum y_i}{n}$

And we can find the intercept using this:

$b=\bar y -m \bar x$

And the model obtained for this case is:

$y = -3.4 +5.2 x$

The correlation coefficient is a "statistical measure that calculates the strength of the relationship between the relative movements of two variables". It's denoted by r and its always between -1 and 1.

And in order to calculate the correlation coefficient we can use this formula:

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

For this case the value of r = -0.66

Now we can calculate the determination coeffcient:

$r^2 = (-0.66)^2 = 0.4356$

And then we can conclude that 43.56% of the variation in y can be explained by the explanatory variable

And then 100-43.56 = 56.44 % of the variation in y that cannot be explained by the explanatory variable

8 0

2 years ago