Since 60 miles per hour is 1 mile a minute so for in 45 minutes he drove 45 miles. After he drove for 50 miles for thirty minutes so in totally he drove 25 since 50 divided by two is 25.

7 0

3 years ago

Sketch the domain D bounded by y = x^2, y = (1/2)x^2, and y=6x. Use a change of variables with the map x = uv, y = u^2 (for u ?

cluponka [151]

Under the given transformation, the Jacobian and its determinant are

$\begin{cases}x=uv\\y=u^2\end{cases}\implies J=\begin{bmatrix}v&u\\2u&0\end{bmatrix}\implies|\det J|=2u^2$

so that

$\displaystyle\iint_D\frac{\mathrm dx\,\mathrm dy}y=\iint_{D'}\frac{2u^2}{u^2}\,\mathrm du\,\mathrm dv=2\iint_{D'}\mathrm du\,\mathrm dv$

where $D'$ is the region $D$ transformed into the $u$ - $v$ plane. The remaining integral is the twice the area of $D'$ .

Now, the integral over $D$ is

$\displaystyle\iint_D\frac{\mathrm dx\,\mathrm dy}y=\left\{\int_0^6\int_{x^2/2}^{x^2}+\int_6^{12}\int_{x^2/2}^{6x}\right\}\frac{\mathrm dx\,\mathrm dy}y$

but through the given transformation, the boundary of $D'$ is the set of equations,

$\begin{array}{l}y=x^2\implies u^2=u^2v^2\implies v^2=1\implies v=\pm1\\y=\frac{x^2}2\implies u^2=\frac{u^2v^2}2\implies v^2=2\implies v=\pm\sqrt2\\y=6x\implies u^2=6uv\implies u=6v\end{array}$

We require that $u>0$ , and the last equation tells us that we would also need $v>0$ . This means $1\le v\le\sqrt2$ and $0$ , so that the integral over $D'$ is

$\displaystyle2\iint_{D'}\mathrm du\,\mathrm dv=2\int_1^{\sqrt2}\int_0^{6v}\mathrm du\,\mathrm dv=\boxed6$

4 0

2 years ago

Mike and Kate plan to save money for their wedding over a 20 month period. They will need to save $8,000 to help pay for the wed

vazorg [7]

-Answer:Option B: Increase the amount of money they save each month by $80 from what they've been saving.

Step-by-step explanation: Only option B will allow them to meet their goal.

7 0

1 year ago

Plz answer this question:

d1i1m1o1n [39]

Yes, Lord Vader !

   2/3 x + 5   = 1/2

Multiply each side by 2 :    4/3 x + 10 = 1

Multiply each side by 3 :    4 x + 30 = 3 <== equivalent equation
      without fractions

Subtract 30 from each side: 4x   = -27

Divide each side by 4 : x      = -27/4 = -6.75

6 0

2 years ago