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3 years ago

10

A bookstore costs $78 a day to keep open, and it spends $14 for each book

2 answers:

Triss [41]3 years ago

5 0

Answer:

13

Step-by-step explanation:

13

RUDIKE [14]3 years ago

5 0

Answer:

B. n= 13

Step-by-step explanation:

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Eric has 5 CDs that he is going to give away. He lets his best friend choose 3 of the 5 CDs. How many different groups of 3 CDs

Snowcat [4.5K]

Given a group of n object. We want to make a selection of k objects out of the n object. This can be done in

C(n, k) many ways, where $C(n, k)= \frac{n!}{k!(n-k)!}$ ,

where k!=1*2*3*...(k-1)*k

Thus, we can do the selection of 3 cd's out of 5, in C(5,3) many ways,

where

$C(5, 3)= \frac{5!}{3!2!}= \frac{5*4*3*2*1}{3*2*1*2*1}= \frac{5*4}{2}=10$

Answer: 10

5 0

3 years ago

Any help with this greatly appreciated.

Anestetic [448]

Put the equation in standard linear form.

$x'(t) + \dfrac{x(t)}{t + 5} = 5e^{5t}$

Find the integrating factor.

$\mu = \exp\left(\displaystyle \int \frac{dt}{t+5}\right) = e^{\ln|t+5|} = t+5$

Multiply both sides by $\mu$ .

$(t+5) x'(t) + x(t) = 5(t+5)e^{5t}$

Now the left side the derivative of a product,

$\bigg((t+5) x(t)\bigg)' = 5(t+5)e^{5t}$

Integrate both sides.

$(t+5) x(t) = \displaystyle 5 \int (t+5) e^{5t} \, dt$

On the right side, integrate by parts.

$(t+5) x(t) = \dfrac15 (5t+24) e^{5t} + C$

Solve for $x(t)$ .

$\boxed{x(t) = \dfrac{5t+24}{5t+25} e^{5t} + \dfrac C{t+5}}$

3 0

2 years ago

Is 4.5 same as 4.50?

Softa [21]

Answer:

Yes

Step-by-step explanation:

0s after all the decimals do not count

4 0

3 years ago

Read 2 more answers

8. Write an equation for the graph in slope-

MrMuchimi

Answer:

The answer is D

Step-by-step explanation:

the y is +10

slope is -1/3

8 0

3 years ago

Hi, can someone please help, and possibly explain the answer please.

mr_godi [17]

Answer:

$x=\frac{-(-2)\±\sqrt{(-2)^2-4(3)(0)} }{2(3)}$

Step-by-step explanation:

Quadratic formula: $x=\frac{-b\±\sqrt{b^2-4ac} }{2a}$ when the equation is $0=ax^2+bx+c$

The given equation is $1=-2x+3x^2+1$ . Let's first arrange this so its format looks like $y=ax^2+bx+c$ :

$1=-2x+3x^2+1$

$1=3x^2-2x+1$

Subtract 1 from both sides of the equation

$1-1=3x^2-2x+1-1\\0=3x^2-2x+0$

Now, we can easily identify 3 as a, -2 as b and 0 as c. Plug these into the quadratic formula:

$x=\frac{-b\±\sqrt{b^2-4ac} }{2a}\\x=\frac{-(-2)\±\sqrt{(-2)^2-4(3)(0)} }{2(3)}$

I hope this helps!

8 0

3 years ago