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kondaur [170]
3 years ago
14

How do i solve equations by substitution?

Mathematics
1 answer:
r-ruslan [8.4K]3 years ago
4 0
Just doing one! Here's my problem:    x-y-11  x-3y=1

So when you subsitute everything it should look like this: 1y-11-3y=1 (There needs to be a one in front of the y because it's just always been there. they don't always put it in the eqation.)  You need to + the 11 and you have to do that to each side. So... 1y-11-3=1
                                                                                                                +11    +11
Now it should look like this: 1y-3y=12
Combine the 1y and -3y to get -4y=12      Last step is divide -4y and 12 by 4  . Answer is y=3
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Suppose that the population​ P(t) of a country satisfies the differential equation dP/dt = kP (600 - P) with k constant. Its pop
jeka94

Answer:

The country's population for the year 2030 is 368.8 million.

Step-by-step explanation:

The differential equation is:

\frac{dP}{dt}=kP(600 - P)\\\frac{dP}{P(600 - P)} =kdt

Integrate the differential equation to determine the equation of P in terms of <em>t</em> as follows:

\int\limits {\frac{1}{P(600-P)} } \, dP =k\int\limits {1} \, dt \\(\frac{1}{600} )[(\int\limits {\frac{1}{P} } \, dP) - (\int\limits {\frac{}{600-P} } \, dP)]=k\int\limits {1} \, dt\\\ln P-\ln (600-P)=600kt+C\\\ln (\frac{P}{600-P} )=600kt+C\\\frac{P}{600-P} = Ce^{600kt}

At <em>t</em> = 0 the value of <em>P</em> is 300 million.

Determine the value of constant C as follows:

\frac{P}{600-P} = Ce^{600kt}\\\frac{300}{600-300}=Ce^{600\times0\times k}\\\frac{1}{300} =C\times1\\C=\frac{1}{300}

It is provided that the population growth rate is 1 million per year.

Then for the year 1961, the population is: P (1) = 301

Then \frac{dP}{dt}=1.

Determine <em>k</em> as follows:

\frac{dP}{dt}=kP(600 - P)\\1=k\times300(600-300)\\k=\frac{1}{90000}

For the year 2030, P (2030) = P (70).

Determine the value of P (70) as follows:

\frac{P(70)}{600-P(70)} = \frac{1}{300} e^{\frac{600\times 70}{90000}}\\\frac{P(70)}{600-P(70)} =1.595\\P(70)=957-1.595P(70)\\2.595P(70)=957\\P(70)=368.786

Thus, the country's population for the year 2030 is 368.8 million.

3 0
3 years ago
Why does -5/10 equal 5/-10 ? explain..
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Answer:

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Step-by-step explanation:

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an athletic sock manufacturer make two different lengths of socks calf length or ankle length. You can buy the socks in navy blu
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A line segment can be drawn between any two points
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4 0
3 years ago
Write the equation of the line that passes through the point (5, -6.5) and is perpendicular to the following equation:
Maslowich
Explanation:
first find the slope m of the line passing through the

the 2 given points
to calculate the slope m use the
gradient formula
∙
x
m
=
y
2
−
y
1
x
2
−
x
1
let
(
x
1
,
y
1
)
=
(
1
,
3
)
and
(
x
2
,
y
2
)
=
(
−
5
,
6
)
m
=
6
−
3
−
5
−
1
=
3
−
6
=
−
1
2
given a line with slope m then the slope of a line

perpendicular to it is
∙
x
m
perpendicular
=
−
1
m
hence
m
perpendicular
=
−
1
−
1
2
=
2
the equation of a line in
slope-intercept form
is.
∙
x
y
=
m
x
+
b
where m is the slope and b the y-intercept
here
m
=
2
y
=
2
x
+
b
←
is the partial equation
to find b substitute
(
−
2
,
7
)
into the partial equation
7
=
−
4
+
b
⇒
b
=
7
+
4
=
11
y
=
2
x
+
11
←
is the required equation
4 0
3 years ago
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