Ask question

Ask question

All categories

3 years ago

14

Write an equation and then use it to solve: Sasha gives half of her books to the local library and keeps the other half. Her bes

t friend gives her 3 more books. She now has 57 books. How many books did she have to begin with?

1 answer:

boyakko [2]3 years ago

8 0

Answer:

120 books

Step-by-step explanation:

57 + 3 = 60

60 x 2 = 120

You might be interested in

Identify the median for the data summarized on the boxplot.

LuckyWell [14K]

Answer:

a.17.5

Step-by-step explanation:

7 0

2 years ago

Read 2 more answers

The profile of the cables on a suspension bridge may be modeled by a parabola. The central span of the bridge is 1210 m long and

brilliants [131]

Answer:

The approximated length of the cables that stretch between the tops of the two towers is 1245.25 meters.

Step-by-step explanation:

The equation of the parabola is:

$y=0.00035x^{2}$

Compute the first order derivative of <em>y</em> as follows:

$y=0.00035x^{2}$

$\frac{\text{d}y}{\text{dx}}=\frac{\text{d}}{\text{dx}}[0.00035x^{2}]$

$=2\cdot 0.00035x\\\\=0.0007x$

Now, it is provided that |<em>x </em>| ≤ 605.

⇒ -605 ≤ <em>x</em> ≤ 605

Compute the arc length as follows:

$\text{Arc Length}=\int\limits^{x}_{-x} {1+(\frac{\text{dy}}{\text{dx}})^{2}} \, dx$

$=\int\limits^{605}_{-605} {\sqrt{1+(0.0007x)^{2}}} \, dx \\\\={\displaystyle\int\limits^{605}_{-605}}\sqrt{\dfrac{49x^2}{100000000}+1}\,\mathrm{d}x\\\\={\dfrac{1}{10000}}}{\displaystyle\int\limits^{605}_{-605}}\sqrt{49x^2+100000000}\,\mathrm{d}x\\\\$

Now, let

$x=\dfrac{10000\tan\left(u\right)}{7}\\\\\Rightarrow u=\arctan\left(\dfrac{7x}{10000}\right)\\\\\Rightarrow \mathrm{d}x=\dfrac{10000\sec^2\left(u\right)}{7}\,\mathrm{d}u$

$\int dx={\displaystyle\int\limits}\dfrac{10000\sec^2\left(u\right)\sqrt{100000000\tan^2\left(u\right)+100000000}}{7}\,\mathrm{d}u$

$={\dfrac{100000000}{7}}}{\displaystyle\int}\sec^3\left(u\right)\,\mathrm{d}u\\\\=\dfrac{50000000\ln\left(\tan\left(u\right)+\sec\left(u\right)\right)}{7}+\dfrac{50000000\sec\left(u\right)\tan\left(u\right)}{7}\\\\=\dfrac{50000000\ln\left(\sqrt{\frac{49x^2}{100000000}+1}+\frac{7x}{10000}\right)}{7}+5000x\sqrt{\dfrac{49x^2}{100000000}+1}$

Plug in the solved integrals in Arc Length and solve as follows:

$\text{Arc Length}=\dfrac{5000\ln\left(\sqrt{\frac{49x^2}{100000000}+1}+\frac{7x}{10000}\right)}{7}+\dfrac{x\sqrt{\frac{49x^2}{100000000}+1}}{2}|_{limits^{605}_{-605}}\\\\$

$=1245.253707795227\\\\\approx 1245.25$

Thus, the approximated length of the cables that stretch between the tops of the two towers is 1245.25 meters.

7 0

3 years ago

Find the centroid for an area defined by the equations y = x² + 3 and y = - (x – 2)² + 7

meriva

The points where the 2 graphs intersect is where x = 0 and x = 2.

- 2 2
x = INT x dA / INT dA
0 0

INT dA = INT -x^2 + 4x + 3 - (x^2 + 3 ) dx = INT -2x^2 + 4x
= -2 x^3/3 + 2x^2
= 2.667 between 0 and 2

xdA = -2x^3 + 4x^2 INT xdA = -x^4/2 + 4x^3/3 = 2.667

centroid = 2.667 / 2.667 = 1 (x = 1)

3 0

3 years ago

Read 2 more answers

Students surveyed about birthdays. How many more students were born on monday than friday?

Varvara68 [4.7K]

C) 2 students
Explanation
Take Monday’s amount and subtract Friday’s
3-1=2

3 0

2 years ago

Bro I don't get this at all

antiseptic1488 [7]

E

2x - 48 = 10x

-2x -2x

-48 = 8x

/8 /8

-6 = x

if you move all of your x's on to the same side it is easier to solve

7 0

3 years ago