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3 years ago

F (x) = x^2 + 2x - 5 g(x) = 2x + 4 What is (f• g)(x)?

Mathematics

1 answer:

Vilka [71]3 years ago

5 0

Answer:

Step-by-step explanation:

This is a composite function, f(g(x)). This means, working from the inside function to the outside, we will take the function g and plug it in for x in the f function. g(x) = 2x + 4. We will plug that into f(x) and evaluate f(2x+4):

$f(g(x))=(2x+4)^2+2(2x+4)-5$ and I imagine your teacher has you simplify completely. We FOIL and distribute to get

$f(g(x))=4x^2+16x+16+4x+8-5$ which, by combining like terms, give us

$f(g(x))=4x^2+20x+19$

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Solve these linear equations by Cramer's Rules Xj=det Bj / det A:

timurjin [86]

Answer:

(a) $x_1=-2,x_2=1$

(b) $x_1=\frac{3}{4} ,x_2=-\frac{1}{2} ,x_3=\frac{1}{4}$

Step-by-step explanation:

(a) For using Cramer's rule you need to find matrix $A$ and the matrix $B_j$ for each variable. The matrix $A$ is formed with the coefficients of the variables in the system. The first step is to accommodate the equations, one under the other, to get $A$ more easily.

$2x_1+5x_2=1\\x_1+4x_2=2$

$\therefore A=\left[\begin{array}{cc}2&5\\1&4\end{array}\right]$

To get $B_1$ , replace in the matrix A the 1st column with the results of the equations:

$B_1=\left[\begin{array}{cc}1&5\\2&4\end{array}\right]$

To get $B_2$ , replace in the matrix A the 2nd column with the results of the equations:

$B_2=\left[\begin{array}{cc}2&1\\1&2\end{array}\right]$

Apply the rule to solve $x_1$ :

$x_1=\frac{det\left(\begin{array}{cc}1&5\\2&4\end{array}\right)}{det\left(\begin{array}{cc}2&5\\1&4\end{array}\right)} =\frac{(1)(4)-(2)(5)}{(2)(4)-(1)(5)} =\frac{4-10}{8-5}=\frac{-6}{3}=-2\\x_1=-2$

In the case of B2, the determinant is going to be zero. Instead of using the rule, substitute the values of the variable $x_1$ in one of the equations and solve for $x_2$ :

$2x_1+5x_2=1\\2(-2)+5x_2=1\\-4+5x_2=1\\5x_2=1+4\\ 5x_2=5\\x_2=1$

(b) In this system, follow the same steps,ust remember $B_3$ is formed by replacing the 3rd column of A with the results of the equations:

$2x_1+x_2 =1\\x_1+2x_2+x_3=0\\x_2+2x_3=0$

$\therefore A=\left[\begin{array}{ccc}2&1&0\\1&2&1\\0&1&2\end{array}\right]$

$B_1=\left[\begin{array}{ccc}1&1&0\\0&2&1\\0&1&2\end{array}\right]$

$B_2=\left[\begin{array}{ccc}2&1&0\\1&0&1\\0&0&2\end{array}\right]$

$B_3=\left[\begin{array}{ccc}2&1&1\\1&2&0\\0&1&0\end{array}\right]$

$x_1=\frac{det\left(\begin{array}{ccc}1&1&0\\0&2&1\\0&1&2\end{array}\right)}{det\left(\begin{array}{ccc}2&1&0\\1&2&1\\0&1&2\end{array}\right)} =\frac{1(2)(2)+(0)(1)(0)+(0)(1)(1)-(1)(1)(1)-(0)(1)(2)-(0)(2)(0)}{(2)(2)(2)+(1)(1)(0)+(0)(1)(1)-(2)(1)(1)-(1)(1)(2)-(0)(2)(0)}\\ x_1=\frac{4+0+0-1-0-0}{8+0+0-2-2-0} =\frac{3}{4} \\x_1=\frac{3}{4}$

$x_2=\frac{det\left(\begin{array}{ccc}2&1&0\\1&0&1\\0&0&2\end{array}\right)}{det\left(\begin{array}{ccc}2&1&0\\1&2&1\\0&1&2\end{array}\right)} =\frac{(2)(0)(2)+(1)(0)(0)+(0)(1)(1)-(2)(0)(1)-(1)(1)(2)-(0)(0)(0)}{4} \\x_2=\frac{0+0+0-0-2-0}{4}=\frac{-2}{4}=-\frac{1}{2}\\x_2=-\frac{1}{2}$

$x_3=\frac{det\left(\begin{array}{ccc}2&1&1\\1&2&0\\0&1&0\end{array}\right)}{det\left(\begin{array}{ccc}2&1&0\\1&2&1\\0&1&2\end{array}\right)}=\frac{(2)(2)(0)+(1)(1)(1)+(0)(1)(0)-(2)(1)(0)-(1)(1)(0)-(0)(2)(1)}{4} \\x_3=\frac{0+1+0-0-0-0}{4}=\frac{1}{4}\\x_3=\frac{1}{4}$

6 0

3 years ago

Solve the inequality: 3/10 is greater than or equal to k - 3/5

Ostrovityanka [42]

To solve the inequality 3/10 is greater than or equal to k - 3/5, we must first set it up. Since 3/10 is greater than or equal to something, we will have a greater than or equal to symbol, with the 'mouth' pointing towards 3/10. Setting this up we get:

3/10 ≥ k - 3/5

Now we want to get k by itself on one side. We can do this by adding 3/5 to each side.

3/10 + 3/5 ≥ k

Simplify

9/10 ≥ k

3 0

3 years ago

a board that is 12 feet long is to be cut into five pieces of equal length. how long will each piece of wood be?

Arte-miy333 [17]

Answer:

2.4 feet long

Step-by-step explanation:

12/5, 12 feet long divided by 5 feet

3 0

2 years ago

Read 2 more answers

Which is the least Pleas help ?!

fiasKO [112]

Answer:

0.35

Step-by-step explanation:

4 0

2 years ago

Read 2 more answers

4.890 in expanded form?

dangina [55]

Answer: The student’s values are accurate as well as precise.

Explanation:

Precision refers to the closeness of two or more measurements to each other.

For Example: If you weigh a given substance three times and you get same value each time. Then the measurement is very precise.

Accuracy refers to the closeness of a measured value to a standard or known value.

For Example: If the mass of a substance is 50 kg and one person weighed 49 kg and another person weighed 48 kg. Then, the weight measured by first person is more accurate.

Given: Mass = 5.000 g

Mass weighed by A has values 4.891 g , 4.901 g and 4.890. Thus the average value is

Thus as the measured value is close to the true value, the student’s values are accurate and as the values are close to each other, the measurement is precise.

6 0

3 years ago