Solve for y <br> 2(y+3)=18

When asked to write a point slope equation for a line passing through the points (-4,-7) and (3,2) a student wrote y-2=-9/7(x-3)

AleksAgata [21]

First let's find the slope
Slope formula:
$\frac{y_2-y_1}{x_2-x_1} =slope$
Given the two coordinates:
(-4,-7) (3,2)
x1,y1 x2,y2

Plug these numbers into the formula
$\frac{2-(-7)}{3-(-4)} = \frac{9}{7}$
In this case the mistake that was made was that the student wrote the slope negative instead of positive
Final answer:
<span>y-2=9/7(x-3)</span>

8 0

3 years ago

Complete the steps of the derivation of the quadratic formula step 1: (x+b/2a)^2-b^2-4ac/4a^2=0

CaHeK987 [17]

(x+b/2a)^2-(b^2-4ac)/2a=0
Step 2:
Re-write the expression:
(x+b/2a)^2=(b^2-4ac)/4a^2

Step 3:
get the square root of both sides:
x+b/2a=sqrt[(b^2-4ac)/4a^2]

Step 4:
Simplifying we get:
x+b/2a=sqrt[b^2-4ac]/2a

Step 5
Make x the subject:
x=-b/2a+/-sqrt[b^2-4ac]/2a

5 0

3 years ago

Read 2 more answers

Let X1 and X2 be independent random variables with mean μand variance σ².

My name is Ann [436]

Answer:

a) $E(\hat \theta_1) =\frac{1}{2} [E(X_1) +E(X_2)]= \frac{1}{2} [\mu + \mu] = \mu$

So then we conclude that $\hat \theta_1$ is an unbiased estimator of $\mu$

$E(\hat \theta_2) =\frac{1}{4} [E(X_1) +3E(X_2)]= \frac{1}{4} [\mu + 3\mu] = \mu$

So then we conclude that $\hat \theta_2$ is an unbiased estimator of $\mu$

b) $Var(\hat \theta_1) =\frac{1}{4} [\sigma^2 + \sigma^2 ] =\frac{\sigma^2}{2}$

$Var(\hat \theta_2) =\frac{1}{16} [\sigma^2 + 9\sigma^2 ] =\frac{5\sigma^2}{8}$

Step-by-step explanation:

For this case we know that we have two random variables:

$X_1 , X_2$ both with mean $\mu = \mu$ and variance $\sigma^2$

And we define the following estimators:

$\hat \theta_1 = \frac{X_1 + X_2}{2}$

$\hat \theta_2 = \frac{X_1 + 3X_2}{4}$

Part a

In order to see if both estimators are unbiased we need to proof if the expected value of the estimators are equal to the real value of the parameter:

$E(\hat \theta_i) = \mu , i = 1,2$

So let's find the expected values for each estimator:

$E(\hat \theta_1) = E(\frac{X_1 +X_2}{2})$

Using properties of expected value we have this:

$E(\hat \theta_1) =\frac{1}{2} [E(X_1) +E(X_2)]= \frac{1}{2} [\mu + \mu] = \mu$

So then we conclude that $\hat \theta_1$ is an unbiased estimator of $\mu$

For the second estimator we have:

$E(\hat \theta_2) = E(\frac{X_1 + 3X_2}{4})$

Using properties of expected value we have this:

$E(\hat \theta_2) =\frac{1}{4} [E(X_1) +3E(X_2)]= \frac{1}{4} [\mu + 3\mu] = \mu$

So then we conclude that $\hat \theta_2$ is an unbiased estimator of $\mu$

Part b

For the variance we need to remember this property: If a is a constant and X a random variable then:

$Var(aX) = a^2 Var(X)$

For the first estimator we have:

$Var(\hat \theta_1) = Var(\frac{X_1 +X_2}{2})$

$Var(\hat \theta_1) =\frac{1}{4} Var(X_1 +X_2)=\frac{1}{4} [Var(X_1) + Var(X_2) + 2 Cov (X_1 , X_2)]$

Since both random variables are independent we know that $Cov(X_1, X_2 ) = 0$ so then we have:

$Var(\hat \theta_1) =\frac{1}{4} [\sigma^2 + \sigma^2 ] =\frac{\sigma^2}{2}$

For the second estimator we have:

$Var(\hat \theta_2) = Var(\frac{X_1 +3X_2}{4})$

$Var(\hat \theta_2) =\frac{1}{16} Var(X_1 +3X_2)=\frac{1}{4} [Var(X_1) + Var(3X_2) + 2 Cov (X_1 , 3X_2)]$

Since both random variables are independent we know that $Cov(X_1, X_2 ) = 0$ so then we have:

$Var(\hat \theta_2) =\frac{1}{16} [\sigma^2 + 9\sigma^2 ] =\frac{5\sigma^2}{8}$

7 0

3 years ago

What is 43x22 in ratio table?

serious [3.7K]

Answer:

A ratio table is a structured list of equivalent (equal value) ratios that helps us understand the relationship between the ratios and the numbers. Rates, like your heartbeat, are a special kind of ratio, where the two compared numbers have different units. Let's look at some examples of ratio table problems.

Step-by-step explanation:

7 0

2 years ago

The sum of two numbers is 25 one number is five less than the other number find the larger number

prohojiy [21]

*NOT MY WORK ITS FROM SOMEONE ELSE WHO ASKED THE SAME PROBLEM*

Answer: x=15, y= 10

Step-by-step explanation:

Answer: x=15, y=10

*Note: x and y are only variables used to solve this problem, but know that the two numbers are 15 and 10.

Step-by-step explanation:

For this problem, we can use system of equations. Let's use x for one number and y for the other.

First Equation:

x+y=25

We get this equation because it states that the sum of the two numbers is 25.

Second Equation:

y=x-5

We get this equation because it says one number (y) is 5 less than the other (x).

Since we have two equations, we can use substitution method to solve.

[distribute 1 to (x-5)]

[combine like terms]

[add both sides by 5]

[divide both sides by 2]

Now that we have x, we can plug it into any of the equations to find y.

[plug in x=15]

[subtract both sides by 15]

Finally, we have our answer, x=15 and y=10.

4 0

2 years ago

Read 2 more answers

Solve for y 2(y+3)=18