Please help me out!!!!!!!!

Mathematics

1 answer:

qaws [65]2 years ago

5 0

Answer:

x = - 6

Step-by-step explanation:

Given that y varies directly as x then the equation relating them is

y = kx ← k is the constant of variation

To find k use the condition y = - 9 when x = 3, thus

k = $\frac{y}{x}$ = $\frac{-9}{3}$ = - 3

y = - 3x ← equation of variation

When y = 18, then

18 = - 3x ( divide both sides by - 3 )

x = - 6

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Which lists all the integer solutions of the inequality |x| < 4?

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Tính tích phân sau bằng cách dùng tọa độ cực I=∫∫ <img src="https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7B%5Csqrt%7Bx%5E%7B2%7D%20%2B

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It sounds like R is the region (in polar coordinates)

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$\displaystyle \iint_R\frac{\mathrm dx\,\mathrm dy}{\sqrt{x^2+y^2}} = \int_0^{\pi/2}\int_2^3 \frac{r\,\mathrm dr\,\mathrm d\theta}{\sqrt{r^2}} \\\\ = \int_0^{\pi/2}\int_2^3 \mathrm dr\,\mathrm d\theta \\\\ = \frac\pi2\int_2^3 \mathrm dr \\\\ = \frac\pi2r\bigg|_2^3 = \frac\pi2 (3-2) = \boxed{\frac\pi2}$