Select the letter of the correct answer.

Can someone please help me with this?

adelina 88 [10]

Answer:

13. x = 12

Step-by-step explanation:

$\frac{16}{x}=\frac{12}{9}$ cross multiply

12x = 144

x = 12

8 0

3 years ago

Use cramers Rule to solve the following system:

Jet001 [13]

Answer:

The solution to the system is $x=1$ , $y=-2$ and $z=-5$

Step-by-step explanation:

Cramer's rule defines the solution of a system of equations in the following way:

$x= \frac{D_x}{D}$ , $y= \frac{D_y}{D}$ and $z= \frac{D_z}{D}$ where $D_x$ , $D_y$ and $D_z$ are the determinants formed by replacing the x,y and z-column values with the answer-column values respectively. $D$ is the determinant of the system. Let's see how this rule applies to this system.

The system can be written in matrix form like:

$\left[\begin{array}{ccc}5&-3&1\\0&2&-3\\7&10&0\end{array}\right]\times \left[\begin{array}{c}x&y&z\end{array}\right] = \left[\begin{array}{c}6&11&-13\end{array}\right]$

Then each of the previous determinants are given by:

$D_x = \left|\begin{array}{ccc}6&-3&1\\11&2&-3\\-13&10&0\end{array}\right|=199$ Notice how the x-column has been substituted with the answer-column one.

$D_y = \left|\begin{array}{ccc}5&6&1\\0&11&-3\\7&-13&0\end{array}\right|=-398$ Notice how the y-column has been substituted with the answer-column one.

$D_z = \left|\begin{array}{ccc}5&-3&6\\0&2&11\\7&10&-13\end{array}\right|=-995$

Then, substituting the values:

$x= \frac{D_x}{D}=\frac{199}{199}\\ x=1$

$x= \frac{D_y}{D}=\frac{-398}{199}\\ y=-2$

$x= \frac{D_z}{D}=\frac{-995}{199}\\ x=-5$

3 0

3 years ago

What are the next 3 numbers in the number sequence?<br> 23,31,41, 53?

aksik [14]

Answer:

61, 71, 83

Step-by-step explanation:

4 0

3 years ago

Read 2 more answers

Toxaphene is an insecticide that has been identified as a pollutant in the Great Lakes ecosystem. To investigate the effect of t

Likurg_2 [28]

Answer:

This data suggest that there is more variability in low-dose weight gains than in control weight gains.

Step-by-step explanation:

Let $\sigma_{1}^{2}$ be the variance for the population of weight gains for rats given a low dose, and $\sigma_{2}^{2}$ the variance for the population of weight gains for control rats whose diet did not include the insecticide.

We want to test $H_{0}: \sigma_{1}^{2} = \sigma_{2}^{2}$ vs $H_{1}: \sigma_{1}^{2} > \sigma_{2}^{2}$ . We have that the sample standard deviation for $n_{2} = 22$ female control rats was $s_{2} = 28$ g and for $n_{1} = 18$ female low-dose rats was $s_{1} = 51$ g. So, we have observed the value

$F = \frac{s_{1}^{2}}{s_{2}^{2}} = \frac{(51)^{2}}{(28)^{2}} = 3.3176$ which comes from a F distribution with $n_{1} - 1 = 18 - 1 = 17$ degrees of freedom (numerator) and $n_{2} - 1 = 22 - 1 = 21$ degrees of freedom (denominator).

As we want carry out a test of hypothesis at the significance level of 0.05, we should find the 95th quantile of the F distribution with 17 and 21 degrees of freedom, this value is 2.1389. The rejection region is given by {F > 2.1389}, because the observed value is 3.3176 > 2.1389, we reject the null hypothesis. So, this data suggest that there is more variability in low-dose weight gains than in control weight gains.

8 0

3 years ago

Which function represents a reflection of f(x)=3/8

Leni [432]

Answer:

Step-by-step explanation:

Reflecting a function across the Y axis means replacing x with -x.

First one could *almost* work, if there wasn't the minus sign at the beginning, so it's a no.

Second one is also a no, the original one is always positive, the second one is always negative.

3rd one is reflecting the graph all right, but it's also adding some sort of stretch (try with the point x=1 in both cases, $f(1) = \frac 32$ while $g_3(1) = 2/3$

4th one is the charm.

8 0

3 years ago