5x + 1 over 2y2

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navik [9.2K]

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5 0

2 years ago

A herd of dinosaurs made paintings in the sand with their claws. Each baby dinosaur made 1515 paintings and each adult dinosaur

mart [117]

Answer:

4 adult dinosaurs and 12 baby dinosaurs.

Step-by-step explanation:

Let the number of adult dinosaurs be x.

Number of baby dinosaurs = 3x

Number of paintings made by each baby dinosaur = 15

Number of paintings made by each adult dinosaur = 7

Total number of paintings made by 3x baby dinosaurs = Number of baby dinosaurs * Number of paintings made by each baby dinosaur

= 3x * 15

= 45x

Total number of paintings made by x adult dinosaurs = Number of adult dinosaurs * Number of paintings made by each adult dinosaur

= x * 7

= 7x

Total number of paintings made by both baby and adult dinosaurs = 45x + 7x

= 52 x

Again the problem says that the total number of paintings made = 208

So, 52x = 208

Dividing both sides by 52

$\frac{52x}{52}$ = $\frac{208}{52}$

Cancelling out the 52's from the top and bottom on the left

x = 4

So, number of adult dinosaurs = 4

Number of baby dinosaurs = 3x = 3*4 = 12

8 0

3 years ago

Find the general solution to each of the following ODEs. Then, decide whether or not the set of solutions form a vector space. E

Ipatiy [6.2K]

Answer:

(A) $y=ke^{2t}$ with $k\in\mathbb{R}$ .

(B) $y=ke^{2t}/2-1/2$ with $k\in\mathbb{R}$

(C) $y=k_1e^{2t}+k_2e^{-2t}$ with $k_1,k_2\in\mathbb{R}$

(D) $y=k_1e^{2t}+k_2e^{-2t}+e^{3t}/5$ with $k_1,k_2\in\mathbb{R}$ ,

Step-by-step explanation

(A) We can see this as separation of variables or just a linear ODE of first grade, then $0=y'-2y=\frac{dy}{dt}-2y\Rightarrow \frac{dy}{dt}=2y \Rightarrow \frac{1}{2y}dy=dt \ \Rightarrow \int \frac{1}{2y}dy=\int dt \Rightarrow \ln |y|^{1/2}=t+C \Rightarrow |y|^{1/2}=e^{\ln |y|^{1/2}}=e^{t+C}=e^{C}e^t} \Rightarrow y=ke^{2t}$ . With this answer we see that the set of solutions of the ODE form a vector space over, where vectors are of the form $e^{2t}$ with $t$ real.

(B) Proceeding and the previous item, we obtain $1=y'-2y=\frac{dy}{dt}-2y\Rightarrow \frac{dy}{dt}=2y+1 \Rightarrow \frac{1}{2y+1}dy=dt \ \Rightarrow \int \frac{1}{2y+1}dy=\int dt \Rightarrow 1/2\ln |2y+1|=t+C \Rightarrow |2y+1|^{1/2}=e^{\ln |2y+1|^{1/2}}=e^{t+C}=e^{C}e^t \Rightarrow y=ke^{2t}/2-1/2$ . Which is not a vector space with the usual operations (this is because $-1/2$ ), in other words, if you sum two solutions you don't obtain a solution.

(C) This is a linear ODE of second grade, then if we set $y=e^{mt} \Rightarrow y''=m^2e^{mt}$ and we obtain the characteristic equation $0=y''-4y=m^2e^{mt}-4e^{mt}=(m^2-4)e^{mt}\Rightarrow m^{2}-4=0\Rightarrow m=\pm 2$ and then the general solution is $y=k_1e^{2t}+k_2e^{-2t}$ with $k_1,k_2\in\mathbb{R}$ , and as in the first items the set of solutions form a vector space.

(D) Using C, let be $y=me^{3t}$ we obtain that it must satisfies $3^2m-4m=1\Rightarrow m=1/5$ and then the general solution is $y=k_1e^{2t}+k_2e^{-2t}+e^{3t}/5$ with $k_1,k_2\in\mathbb{R}$ , and as in (B) the set of solutions does not form a vector space (same reason! as in (B)).

4 0

3 years ago

What is the surface area of this triangular prism shown above?

PIT_PIT [208]

To find the surface are of the base: 8 * 8 = 64/2(becasue its a triangle not a square base) = 32.
To find the surface are of the 3 other faces, 12 * 8 = 96/2 = 48 * 3(for the 3 sides) = 144.
The entire surface area is 176.

4 0

3 years ago

Robbie, has scored 120 so far this season. He has scored all of his points on 1-point extra point kicks and 3-point field goals.

joja [24]

Answer:

39 and 27

Step-by-step explanation:

GIVEN: Robbie, has scored $120$ so far this season. He has scored all of his points on $1$ -point extra point kicks and $3$ -point field goals. He has made a total of $66$ kicks.