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Radda [10]
4 years ago
9

Find the determinant of the nxn matrix A with 5's on the diagonal, l's above the diagonal, and O's below the diagonal. det (A) =

Mathematics
1 answer:
Vilka [71]4 years ago
6 0

Answer:

n times 5

Step-by-step explanation:

A matrix Anxn of this way is called an upper triangular matrix. It can be proved that the determinant of this kind of matrix is  

a_{11}+a_{22}+...+a_{nn}

In this case, it would be 5+5+...+5 (n times) = n times 5

We are going to develop each determinant by the first column taking as pivot points the elements of the diagonal

det\left[\begin{array}{cccc}5&a_{12}&a_{13}...&a_{1n}\\0&5&a_{23}...&a_{2n}\\...&...&...&...\\0&0&0&5\end{array}\right] =5+det\left[\begin{array}{ccc}5&a_{23}...&a_{2n}\\0&5&a_{3n}\\...&...&...\\0&0&5\end{array}\right]=5+5+...+det\left[\begin{array}{cc}5&a_{n-1,n}\\0&5\end{array}\right]=5+5+...+5+5\;(n\;times)

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The cube root of 5 times the square root of 5 over the cube root of 5 to the 5th power
Fiesta28 [93]
(cube root of 5)  * sqrt(5)
--------------------------------- = ?
(cube root of 5^5)

This becomes easier if we switch to fractional exponents:


  5^(1/3) * 5^(1/2)         5^(1/3 + 1/2)       5^(5/6)
------------------------ = --------------------- = ------------- = 5^[5/6 - 5/3]
[ 5^5 ]^(1/3)                  5^(5/3)                 5^(5/3) 

Note that 5/6 - 5/3 = 5/6 - 10/6 = -5/6.

                                                            1
Thus,  5^[5/6 - 5/3] = 5^(-5/6)  =  --------------
                                                        5^(5/6)

That's the correct answer.  But if you want to remove the fractional exponent from the denominator, do this:

    1            5^(1/6)         5^(1/6)
---------- * ------------- = --------------    (ANSWER)
5^(5/6)       5^(1/6)              5
7 0
4 years ago
What is an equation of the line that passes through the points (4,-1) and (8,5)?
fiasKO [112]

Answer:

y=3/2x-7

Step-by-step explanation:

the equation of the line for slope-intercept form is y=mx+b, where  m is the slope and b is the y intercept.

we are given two points: (4,-1) and (8,5)

the equation for slope is (y2-y1)/(x2-x1)

label the points:

x1=4

y1=-1

x2=8

y2=5

now substitute into the equation:

m=(5--1)/(8-4)

m=6/4

m=3/2

the slope of the line is 3/2

here is our equation so far:

y=3/2x+b

we need to find b

since the equation will pass through the points, we can substitute either one into the equation to find b

let's use (4,-1) as an example

substitute into the equation

-1=3/2(4)+b

-1=6+b

-7=b

the y intercept is -7

so the equation is y=3/2x-7

hope this helps!

8 0
3 years ago
A number is first increased by 20 and then doubled. The result is 2 less than 5 times
Iteru [2.4K]

i  think maybe ? x+20*2=5-2*x

8 0
3 years ago
I need help with this will mark u as brainliest.
Amanda [17]
1. B
2. A
3. D
4. D
I'm not too sure about 1 but I'm sure about the others. Hope this helps!
7 0
3 years ago
Rewrite the expression 15(8 - 2) using the distributive property.
Charra [1.4K]

Answer:

9

Step-by-step explanation:

15(8-2)

15-(6)

9

4 0
3 years ago
Read 2 more answers
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