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2 years ago

Solve the system of equations using substitution: 6x – y = –15 X + 2y = 17

Mathematics

1 answer:

defon2 years ago

3 0

Answer:

x = -1

y = 9

Step-by-step explanation:

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Use the given transformation x=4u, y=3v to evaluate the integral. ∬r4x2 da, where r is the region bounded by the ellipse x216 y2

exis [7]

The Jacobian for this transformation is

$J = \begin{bmatrix} x_u & x_v \\ y_u & y_v \end{bmatrix} = \begin{bmatrix} 4 & 0 \\ 0 & 3 \end{bmatrix}$

with determinant $|J| = 12$ , hence the area element becomes

$dA = dx\,dy = 12 \, du\,dv$

Then the integral becomes

$\displaystyle \iint_{R'} 4x^2 \, dA = 768 \iint_R u^2 \, du \, dv$

where $R'$ is the unit circle,

$\dfrac{x^2}{16} + \dfrac{y^2}9 = \dfrac{(4u^2)}{16} + \dfrac{(3v)^2}9 = u^2 + v^2 = 1$

so that

$\displaystyle 768 \iint_R u^2 \, du \, dv = 768 \int_{-1}^1 \int_{-\sqrt{1-v^2}}^{\sqrt{1-v^2}} u^2 \, du \, dv$

Now you could evaluate the integral as-is, but it's really much easier to do if we convert to polar coordinates.

$\begin{cases} u = r\cos(\theta) \\ v = r\sin(\theta) \\ u^2+v^2 = r^2\\ du\,dv = r\,dr\,d\theta\end{cases}$

Then

$\displaystyle 768 \int_{-1}^1 \int_{-\sqrt{1-v^2}}^{\sqrt{1-v^2}} u^2\,du\,dv = 768 \int_0^{2\pi} \int_0^1 (r\cos(\theta))^2 r\,dr\,d\theta \\\\ ~~~~~~~~~~~~ = 768 \left(\int_0^{2\pi} \cos^2(\theta)\,d\theta\right) \left(\int_0^1 r^3\,dr\right) = \boxed{192\pi}$

3 0

1 year ago

ada recorded the thickness a of a set of books. This line plot shows her results. Jada stacked the books that were 112 inches th

Sergeu [11.5K]

Good game play later

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2 years ago

( Will give Brainliest) Please Helpp

gogolik [260]

Answer:

8cm

Step-by-step explanation:

Area of a triangle equals bh/2

If you plug in the data, you get

10= $\frac{5}{2}$ * $\frac{h}{2}$

10= $\frac{5h}{4}$

40=5h

h=8

6 0

3 years ago

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a company pays 75% of each employee's Medical Care premium if the employee portion is $50 for a month and there are 100 employee

Romashka-Z-Leto [24]

Hope this helps
THE COMPANY PAY EACH MONTH FOR EMPLOYEE MEDICAL BENEFITS? can u ... $200 - $50 = $150 paid by company per employee ... For each employee the company pays 75%

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3 years ago

How long must $542 be invested at a rate of 7 percent to earn a 303.52 interest

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How long must $542 be invested at a rate of 7 percent to earn a 303.52 interest

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