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3 years ago

Select the correct answer.

Mathematics

1 answer:

Gre4nikov [31]3 years ago

4 0

Answer:

(D) These two matrices cannot be added.

Step-by-step explanation:

Matrices of different shapes can't be added, but they can be multiplied. : ) Have a good day.

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mr. ken's class is collecting empty water bottles. they started with 17 water bottles on day 1. on day 3, they had 30 water bott

Oxana [17]

They had 23 and 38 water bottles on day 2 and day 4 respectively. Also, there will be 68 water bottles on day 7.

Explanation

Suppose, the equation representing the number of bottles is $y= ax^2 +bx+c$ , where $x$ is the number of days.

There are 17 water bottles on day 1, 30 water bottles on day 3 and 47 water bottles on day 5

So, the three points in the form of (x, y) are: (1, 17) , (3, 30) and (5, 47)

Plugging these three points into the above equation, we will get .....

$17=a(1)^2 + b(1) +c\\ a+b+c=17 ............................ (1)\\ \\ 30=a(3)^2+b(3)+c\\ 9a+3b+c=30 ......................... (2) \\ \\ 47=a(5)^2+b(5)+c\\ 25a+5b+c=47 ......................... (3)$

Subtracting equation (1) from equation (2) , we will get .....

$8a+2b=13 ..................... (4)$

Subtracting equation (2) from equation (3) , we will get .....

$16a+2b=17 ...................... (5)$

Now, subtracting equation (4) from equation (5) , we will get ......

$16a -8a = 17-13\\ \\ 8a= 4\\ \\ a=\frac{4}{8}= 0.5$

Substituting this $a= 0.5$ into equation (4) ........

$8(0.5)+2b=13\\ \\ 4+2b=13\\ \\ 2b=9\\ \\ b=\frac{9}{2}=4.5$

Again, substituting $a=0.5$ and $b=4.5$ into equation (1) , we will get ......

$0.5+4.5+c=17\\ \\ 5+c=17\\ \\ c=17-5 =12$

So, the equation will be now: $y= 0.5x^2 +4.5x+12$

For finding the number of bottles on day 2 , day 4 and day 7 , we need to plug $x=2 , 4, 7$ respectively into the above equation.

For $x= 2$ , $y= 0.5(2)^2 +4.5(2)+12 = 2+9+12= 23$

For $x= 4$ , $y= 0.5(4)^2 +4.5(4)+12 = 8+18+12= 38$

For $x= 7$ , $y= 0.5(7)^2 +4.5(7)+12 = 24.5+31.5+12= 68$

So, they had 23 water bottles on day 2 and 38 water bottles on day 4

Also, there will be 68 water bottles on day 7

6 0

3 years ago

Solve equation and write reason for each step x+25=45

alexdok [17]

just do 45-25= x

x= 20

4 0

3 years ago

Read 2 more answers

PLEASE HELP!!! WILL GIVE BRAINILEST

Elina [12.6K]

Answer:

the answer is C

Step-by-step explanation:

the equation of a line is y-y1=m(x-x1) where x1 and y1 are points on a line

so when you compare the two equations, you get C

3 0

3 years ago

Packaging By cutting away identical squares from each corner of a rectangular piece of cardboard and folding up the resulting fl

Kobotan [32]

Answer:

The dimension of the box is 18.66 in by 2.66 in by 1.17 in.

Step-by-step explanation:

Given that, The cardboard is 21 in. long and 5 in. wide.

Assume,x be the length of the each sides of the square .

Then the length of the box is = (21-2x) in.

The breadth of the box is =(5-2x) in.

The height of the box is = length of side of the square

= x in.

The volume of the box = length × wide × height

=(21-2x)(5-2x)x

=(105-52x+4x²)x

=( $105 x-52x^2+4x^3$ )

Let

V= $105 x-52x^2+4x^3$

Differentiating with respect to x

$V'=105-104x+12x^2$

Again differentiating with respect to x

$V''=-104+24x$

To find the dimension of the box, we set V'=0

$105-104x+12x^2=0$

Applying the quadratic formula $x=\frac{-b\pm \sqrt{b^2-4ac}}{2a}$ , here a=12, b= -104 and c =105

$\Rightarrow x=\frac{-(-104)\pm\sqrt{(-104)^2-4.12.105}}{2.12}$

$=\frac{104\pm 76}{24}$

=7.5, 1.17

For x= 7.5 , the wide of the box will be negative.

∴x=1.17 in.

$V''_{x=1.17}=-104+(24\times 1.17)$

Since at x= 1.17, V''<0 , therefore at x=1.17 in. the volume of the given box will be maximum.

The length of the box is = [21-(1.17×2)]=18.66 in.

The wide of the box is = [5-(1.17×2)]=2.66 in.

The height of the box is = 1.17 in.

The dimension of the box is 18.66 in by 2.66 in by 1.17 in.

5 0

4 years ago

A geodesic dome has a radius of 54 feet. What is the volume of the dome? Use 3.14 for pi.

dimulka [17.4K]

Answer:

Modeling the dome as a hemisphere, V = 2/3 πr³ =

(2/3)(3.14)(54 ft)³ = 629,624.64 ft³

Step-by-step explanation:

5 0

3 years ago