Simplify 4(x+7) - 7x+ 2. A. 11x+9 B. 11x+30 C. -3x+30 D. -3x+9

4. Emily ate dinner at Geisha. Her total was $17.50. A 8% sales tax was

Ahat [919]

Answer: $22.68

Step-by-step explanation:

17.50 times 0.08 = 1.40

17.50 + 1.40 = 18.90

Now the tip:

18.90 times .2 = 3.78

18.90 + 3.78 = 22.68

5 0

3 years ago

37. Verify Green's theorem in the plane for f (3x2- 8y2) dx + (4y - 6xy) dy, where C is the boundary of the

Nastasia [14]

I'll only look at (37) here, since

• (38) was addressed in 24438105

• (39) was addressed in 24434477

• (40) and (41) were both addressed in 24434541

In both parts, we're considering the line integral

$\displaystyle \int_C (3x^2-8y^2)\,\mathrm dx + (4y-6xy)\,\mathrm dy$

and I assume C has a positive orientation in both cases

(a) It looks like the region has the curves y = x and y = x ² as its boundary***, so that the interior of C is the set D given by

$D = \left\{(x,y) \mid 0\le x\le1 \text{ and }x^2\le y\le x\right\}$

• Compute the line integral directly by splitting up C into two component curves,

C₁ : x = t and y = t ² with 0 ≤ t ≤ 1

C₂ : x = 1 - t and y = 1 - t with 0 ≤ t ≤ 1

Then

$\displaystyle \int_C = \int_{C_1} + \int_{C_2} \\\\ = \int_0^1 \left((3t^2-8t^4)+(4t^2-6t^3)(2t))\right)\,\mathrm dt \\+ \int_0^1 \left((-5(1-t)^2)(-1)+(4(1-t)-6(1-t)^2)(-1)\right)\,\mathrm dt \\\\ = \int_0^1 (7-18t+14t^2+8t^3-20t^4)\,\mathrm dt = \boxed{\frac23}$

*** Obviously this interpretation is incorrect if the solution is supposed to be 3/2, so make the appropriate adjustment when you work this out for yourself.

• Compute the same integral using Green's theorem:

$\displaystyle \int_C (3x^2-8y^2)\,\mathrm dx + (4y-6xy)\,\mathrm dy = \iint_D \frac{\partial(4y-6xy)}{\partial x} - \frac{\partial(3x^2-8y^2)}{\partial y}\,\mathrm dx\,\mathrm dy \\\\ = \int_0^1\int_{x^2}^x 10y\,\mathrm dy\,\mathrm dx = \boxed{\frac23}$

(b) C is the boundary of the region

$D = \left\{(x,y) \mid 0\le x\le 1\text{ and }0\le y\le1-x\right\}$

• Compute the line integral directly, splitting up C into 3 components,

C₁ : x = t and y = 0 with 0 ≤ t ≤ 1

C₂ : x = 1 - t and y = t with 0 ≤ t ≤ 1

C₃ : x = 0 and y = 1 - t with 0 ≤ t ≤ 1

Then

$\displaystyle \int_C = \int_{C_1} + \int_{C_2} + \int_{C_3} \\\\ = \int_0^1 3t^2\,\mathrm dt + \int_0^1 (11t^2+4t-3)\,\mathrm dt + \int_0^1(4t-4)\,\mathrm dt \\\\ = \int_0^1 (14t^2+8t-7)\,\mathrm dt = \boxed{\frac53}$

• Using Green's theorem:

$\displaystyle \int_C (3x^2-8y^2)\,\mathrm dx + (4y-6xy)\,\mathrm dx = \int_0^1\int_0^{1-x}10y\,\mathrm dy\,\mathrm dx = \boxed{\frac53}$

4 0

3 years ago

4. ADEF is an equilateral triangle. E 24 20 D F

irinina [24]

By Pythagorean theorem

x²+GF²=EF² ( where G is the point of intersection of perpendicular lines)

now, GF=1/2 EF= 12

x²+12²=24²

x²=24²-12²

x²=432

x=√432

x=12√3

x≈20.78

7 0

3 years ago

Find the derivative of StartFraction d Over dx EndFraction Integral from 0 to x cubed e Superscript negative t Baseline font siz

Valentin [98]

Answer: (a) e ^ -3x (b)e^-3x

Step-by-step explanation:

I suggest the equation is:

d/dx[integral (e^-3t) dt

First we integrate e^-3tdt

Integral(e ^ -3t dt) as shown in attachment and then we differentiate the result as shown in the attachment.

(b) to differentiate the integral let x = t, and substitute into the expression.

Therefore dx = dt

Hence, d/dx[integral (e ^-3x dx)] = e^-3x

8 0

4 years ago

Read 2 more answers

If a x 10^n is scientific notation, then a must be between 1 and

Yanka [14]

Answer:

A) 10

Step-by-step explanation:

In the US, a number in scientific notation will have a mantissa (a) such that ...

1 ≤ a < 10

That is, the value of "a" must be between 1 and 10 (not including 10).

_____

Comment on alternatives

In other places or in particular applications (some computer programming languages), the standard form of the number may be a×10^n with ...

0.1 ≤ a < 1

In engineering use, the form of the number is often chosen so that "n" is a multiple of 3, and "a" is in the range ...

1 ≤ a < 1000

This makes it easier to identify and use the appropriate standard SI prefix: nano-, micro-, milli-, kilo-, mega-, giga-, and so on.

4 0

3 years ago