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3 years ago

Solve using derivatives.

Mathematics

1 answer:

Bond [772]3 years ago

7 0

Answer:

Below in bold.

Step-by-step explanation:

The surface area of the box

= x^2 + 4hx where x = a side of the square base and h is the height.

So x^2 + 4hx = 8

The volume of the box

V = x^2h

From the first equation we solve for h

4hx = 8 - x^2

h = (8 - x^2) / 4x

Now we substitute for h in the formula for the volume:

V = x^2 * (8 - x^2) / 4x

V = 8x^2 - x^4 / 4x

V = 2x - 0.25x^3

Finding the derivative:

V' = 2 - 0.75x^2 = 0 for max/mimn values

x^2 = 2/ 0.75 = 2.667

x = 1.633.

So the length and width of the base is 1.633 m and the height

= ( 8 - 2.667) / (4*1.633)

= 0.816 m

The maximum volume = 0.816 * 2.667 = 2.177 m^2.

The answers are correct to the nearest thousandth.

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Find two integers whose sum is -20 and product is 99

Brums [2.3K]

Answer:

Step-by-step explanation:

let the integers be x and y

x+y=-20

y=-20-x

xy=99

x(-20-x)=99

-20x-x²=99

x²+20x+99=0

x²+11x+9x+99=0

x(x+11)+9(x+11)=0

(x+11)(x+9)=0

x=-11,-9

when x=-11

-11+y=-20

y=-20=11=-9

when x=-9

-9+y=-20

y=-20+9=-11

so integers are -11,-9

8 0

3 years ago

Read 2 more answers

Which shape has only acute angles?

olga nikolaevna [1]

The triangle has an only acute angle

5 0

3 years ago

PLEASE HELP !! ILL GIVE BRAINLIEST *EXTRA POINTS*.. IM GIVING 40 POINTS !! DONT SKIP :((.

melomori [17]

8, and 57 I believe am sorry if am wrong I didn’t mean to get it wrong

7 0

3 years ago

To test whether or not there is a difference between treatments A, B, and C, a sample of 12 observations has been randomly assig

Keith_Richards [23]

Answer:

1. Null hypothesis: $\mu_{A}=\mu_{B}=\mu_{C}$

Alternative hypothesis: Not all the means are equal $\mu_{i}\neq \mu_{j}, i,j=A,B,C$

2. D. 36

3. C. 34

4. B. 1.059

5. B. 8.02

Step-by-step explanation:

Analysis of variance (ANOVA) "is used to analyze the differences among group means in a sample".

The sum of squares "is the sum of the square of variation, where variation is defined as the spread between each individual value and the grand mean"

Part 1

The hypothesis for this case are:

Null hypothesis: $\mu_{A}=\mu_{B}=\mu_{C}$

Alternative hypothesis: Not all the means are equal $\mu_{i}\neq \mu_{j}, i,j=A,B,C$

Part 2

In order to find the mean square between treatments (MSTR), we need to find first the sum of squares and the degrees of freedom.

If we assume that we have $p$ groups and on each group from $j=1,\dots,p$ we have $n_j$ individuals on each group we can define the following formulas of variation:

$SS_{total}=\sum_{j=1}^p \sum_{i=1}^{n_j} (x_{ij}-\bar x)^2$

$SS_{between}=SS_{model}=\sum_{j=1}^p n_j (\bar x_{j}-\bar x)^2$

$SS_{within}=SS_{error}=\sum_{j=1}^p \sum_{i=1}^{n_j} (x_{ij}-\bar x_j)^2$

And we have this property

$SST=SS_{between}+SS_{within}$

We need to find the mean for each group first and the grand mean.

$\bar X =\frac{\sum_{i=1}^n x_i}{n}$

If we apply the before formula we can find the mean for each group

$\bar X_A = 27$ , $\bar X_B = 24$ , $\bar X_C = 30$ . And the grand mean $\bar X = 27$

Now we can find the sum of squares between:

$SS_{between}=SS_{model}=\sum_{j=1}^p n_j (\bar x_{j}-\bar x)^2$

Each group have a sample size of 4 so then $n_j =4$

$SS_{between}=SS_{model}=4(27-27)^2 +4(24-27)^2 +4(30-27)^2=72$

The degrees of freedom for the variation Between is given by $df_{between}=k-1=3-1=2$ , Where k the number of groups k=3.

Now we can find the mean square between treatments (MSTR) we just need to use this formula:

$MSTR=\frac{SS_{between}}{k-1}=\frac{72}{2}=36$

D. 36

Part 3

For the mean square within treatments value first we need to find the sum of squares within and the degrees of freedom.

$SS_{within}=SS_{error}=\sum_{j=1}^p \sum_{i=1}^{n_j} (x_{ij}-\bar x_j)^2$

$SS_{error}=(20-27)^2 +(30-27)^2 +(25-27)^2 +(33-27)^2 +(22-24)^2 +(26-24)^2 +(20-24)^2 +(28-24)^2 +(40-30)^2 +(30-30)^2 +(28-30)^2 +(22-30)^2 =306$

And the degrees of freedom are given by:

$df_{within}=N-k =3*4 -3 = 12-3=9$ . N represent the total number of individuals we have 3 groups each one with a size of 4 individuals. And k the number of groups k=3.

And now we can find the mean square within treatments:

$MSE=\frac{SS_{within}}{N-k}=\frac{306}{9}=34$

C. 34

Part 4

The test statistic F is given by this formula:

$F=\frac{MSTR}{MSE}=\frac{36}{34}=1.059$

B. 1.059

Part 5

The critical value is from a F distribution with degrees of freedom in the numerator of 2 and on the denominator of 9 such that we have 0.01 of the area in the distribution on the right.

And we can use excel to find this critical value with this function:

"=F.INV(1-0.01,2,9)"

And we will see that the critical value is $F_{crit}=8.02$

B. 8.02

5 0

3 years ago

Estimate to the nearest integer. 21 O 3 O 4 O 5

Rudiy27

Answer:

Step-by-step explanation:

So the square root of 21 is 4.582...

If you round 4.582.. it is 5

Because you look at the first number behind the decimal (tenths place) if it is 4-0 you leave the number the same. If it is 5-9 you increase the number by 1.

Hope this helps ya!!

4 0

3 years ago