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3 years ago

What is (x+7)(x-4) simplified

2 answers:

fomenos3 years ago

5 0

(x + 7) (x - 4)

First, apply the FOIL method (a + b) (c + d) = ac + ad + bc + bd / Your problem should look like: $x^{2}$ - 4x + 7x - 28
Second, gather the like terms. / Your problem should look like: $x^{2}$ + (-4x + 7x) - 28
Third, simplify. / Your problem should look like: $x^{2}$ + 3x - 28

Answer: $x^{2}$ + 3x - 28

Sidana [21]3 years ago

5 0

(x+7)(x−4)

=(x+7)(x+−4)

=(x)(x)+(x)(−4)+(7)(x)+(7)(−4)

=x^2−4x+7x−28

=x^2+3x−28

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Find the average of 60 75 88 and 93

Lapatulllka [165]

Answer:

The average of the four numbers is 79.

4 0

3 years ago

A common assumption in modeling drug assimilation is that the blood volume in a person is a single compartment that behaves like

mixas84 [53]

Answer:

a) $\mathbf{\dfrac{dx}{dt} = 30 - 0.015 x}$

b) $\mathbf{x = 2000 - 2000e^{-0.015t}}$

c) the steady state mass of the drug is 2000 mg

d) t ≅ 153.51 minutes

Step-by-step explanation:

From the given information;

At time t= 0

an intravenous line is inserted into a vein (into the tank) that carries a drug solution with a concentration of 500

The inflow rate is 0.06 L/min.

Assume the drug is quickly mixed thoroughly in the blood and that the volume of blood remains constant.

The objective of the question is to calculate the following :

a) Write an initial value problem that models the mass of the drug in the blood for t ≥ 0.

From above information given :

$Rate _{(in)}= 500 \ mg/L \times 0.06 \ L/min = 30 mg/min$

$Rate _{(out)}=\dfrac{x}{4} \ mg/L \times 0.06 \ L/min = 0.015x \ mg/min$

Therefore;

$\dfrac{dx}{dt} = Rate_{(in)} - Rate_{(out)}$

with respect to x(0) = 0

$\mathbf{\dfrac{dx}{dt} = 30 - 0.015 x}$

b) Solve the initial value problem and graph both the mass of the drug and the concentration of the drug.

$\dfrac{dx}{dt} = -0.015(x - 2000)$

$\dfrac{dx}{(x - 2000)} = -0.015 \times dt$

By Using Integration Method:

$ln(x - 2000) = -0.015t + C$

$x -2000 = Ce^{(-0.015t)$

$x = 2000 + Ce^{(-0.015t)}$

However; if x(0) = 0 ;

Then

C = -2000

Therefore

$\mathbf{x = 2000 - 2000e^{-0.015t}}$

c) What is the steady-state mass of the drug in the blood?

the steady-state mass of the drug in the blood when t = infinity

$\mathbf{x = 2000 - 2000e^{-0.015 \times \infty }}$

x = 2000 - 0

x = 2000

Thus; the steady state mass of the drug is 2000 mg

d) After how many minutes does the drug mass reach 90% of its stead-state level?

After 90% of its steady state level; the mas of the drug is 90% × 2000

= 0.9 × 2000

= 1800

Hence;

$\mathbf{1800 = 2000 - 2000e^{(-0.015t)}}$

$0.1 = e^{(-0.015t)$

$ln(0.1) = -0.015t$

$t = -\dfrac{In(0.1)}{0.015}$

t = 153.5056729

t ≅ 153.51 minutes

4 0

3 years ago

A study was conducted to determine whether a new highway should be built next to the river in a town. Half of the residents in t

Tamiku [17]

Answer:

The sampling of this study is bias

Step-by-step explanation:

Sampling bias is a bias that is gotten during sampling where some members of the population have a lower representation or probability than others in the sample pool. In this case, only the residents living near a river was sampled, and because they are subjected to relatively the same conditions (living near a river), the result of the study will not be a true representation of every member of the town because the people living far away from the river will most likely have different opinions due to their different environmental exposure than the people living close to the river. The correct thing to have been done for the result to be reliable and accurate will be to sample at random, people in the two both close to and far away from the river, or to sample equal number of people each living close to and far away from the river.

Another example of sampling bias is a study to determine the effect of alcohol on pregnancy in women in America, and only pregnant white women who drink are sampled, leaving out Black or Hispanic women, what ever result gotten in the study may hold true for white women in America, but it may not hold true for every woman in America

8 0

3 years ago

If you’re ADDING same bases, then you should also ADD the exponents. <br><br> True<br> False

Arisa [49]

False when you multiply numbers you add the exponents.

6 0

3 years ago

What is 2X +7 = 5X -8

inna [77]

Answer:

X=5

Step-by-step explanation:

2X+7=5X-8

7=3X-8

15=3X

5=X

5 0

3 years ago

Read 2 more answers