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2 years ago

Solve the system is of linear equations by substitution.What is the solution to x=2y+7 and 3x+2y=3?

Mathematics

1 answer:

babymother [125]2 years ago

4 0

Answer:

(5/2, -9/4)

Step-by-step explanation:

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I can't seem to figure out number 13, with the star. I just don't know! Help is very appreciated ☺️

katrin2010 [14]

Given:
Scale of the map 1 1/4cm : 8 yards
Rectangular Park: width : 2 1/2 cm ; length : 6 1/4 cm
Circular Pond: pi = 3.14 ; diameter 1 1/4 cm

Convert mixed factions into fractions.
Scale 1 1/4 = (4*1+1)/4 = 5/4
Width: 2 1/2 = (2*2+1)/2 = 5/2
Length: 6 1/4 = (4*6+1)/4 = 25/4
Diameter: 1 1/4 = (4*1+1)/4 = 5/4

width / scale * 8 yds = width in yards
5/2 ÷ 5/4 = 5/2 * 4/5 = 20/10 = 2 * 8 yds = 16 yds
length / scale * 8 yds = length in yards
25/4 ÷ 5/4 = 25/4 * 4/5 = 100/20 = 5 * 8 yds = 40 yds

Area of a rectangular park = l * w = 40 yds * 16 yds = 640 yds²

diameter / scale * 8 yds = diameter in yards
5/4 ÷ 5/4 = 5/4 * 4/5 = 20/20 = 1 * 8 yds = 8 yds.

radius = d/2 = 8/2 = 4
Area of a circular pond = πr² = 3.14 * 4² = 3.14 * 16yds² = 50.24 yds²

5 0

2 years ago

What two terms are being multiplied in the expression 6(p + 7q)?

Korvikt [17]

C because PEMDAS
(Please excuse my dear aunt sally)

7 0

3 years ago

The volume of a sphere is 2 comma 143.57 m cubed. To the nearest meter, what is the radius of the sphere? Use 3.14 for pi.

miskamm [114]

$\bf \textit{volume of a sphere}\\\\ V=\cfrac{4\pi r^3}{3}~~ \begin{cases} r=radius\\ \cline{1-1} V=2,143.57 \end{cases}\implies 2143.57=\cfrac{4\pi r^3}{3}\implies 6430.71=4\pi r^3 \\\\\\ \cfrac{6430.71}{4\pi }=r^3\implies \sqrt[3]{\cfrac{6430.71}{4\pi }}=r\implies \stackrel{\pi =3.14}{7.9999956 \approx r}\implies \stackrel{\textit{rounded up}}{8=r}$

7 0

3 years ago

A swimming pool with a volume of 30,000 liters originally contains water that is 0.01% chlorine (i.e. it contains 0.1 mL of chlo

SpyIntel [72]

Answer:

$R_{in}=0.2\dfrac{mL}{min}$

$C(t)=\dfrac{A(t)}{30000}$

$R_{out}= \dfrac{A(t)}{1500} \dfrac{mL}{min}$

$A(t)=300+2700e^{-\dfrac{t}{1500}},$ A(0)=3000$

Step-by-step explanation:

The volume of the swimming pool = 30,000 liters

(a) Amount of chlorine initially in the tank.

It originally contains water that is 0.01% chlorine.

0.01% of 30000=3000 mL of chlorine per liter

A(0)= 3000 mL of chlorine per liter

(b) Rate at which the chlorine is entering the pool.

City water containing 0.001%(0.01 mL of chlorine per liter) chlorine is pumped into the pool at a rate of 20 liters/min.

$R_{in}=$ (concentration of chlorine in inflow)(input rate of the water)

$=(0.01\dfrac{mL}{liter}) (20\dfrac{liter}{min})\\R_{in}=0.2\dfrac{mL}{min}$

Volume of the pool =30,000 Liter

$Concentration, C(t)= \dfrac{Amount}{Volume}\\C(t)=\dfrac{A(t)}{30000}$

(d) Rate at which the chlorine is leaving the pool

$R_{out}=$ (concentration of chlorine in outflow)(output rate of the water)

$= (\dfrac{A(t)}{30000})(20\dfrac{liter}{min})\\R_{out}= \dfrac{A(t)}{1500} \dfrac{mL}{min}$

(e) Differential equation representing the rate at which the amount of sugar in the tank is changing at time t.

$\dfrac{dA}{dt}=R_{in}-R_{out}\\\dfrac{dA}{dt}=0.2- \dfrac{A(t)}{1500}$

We then solve the resulting differential equation by separation of variables.

$\dfrac{dA}{dt}+\dfrac{A}{1500}=0.2\\$The integrating factor: e^{\int \frac{1}{1500}dt} =e^{\frac{t}{1500}}\\$Multiplying by the integrating factor all through\\\dfrac{dA}{dt}e^{\frac{t}{1500}}+\dfrac{A}{1500}e^{\frac{t}{1500}}=0.2e^{\frac{t}{1500}}\\(Ae^{\frac{t}{1500}})'=0.2e^{\frac{t}{1500}}$

Taking the integral of both sides

$\int(Ae^{\frac{t}{1500}})'=\int 0.2e^{\frac{t}{1500}} dt\\Ae^{\frac{t}{1500}}=0.2*1500e^{\frac{t}{1500}}+C, $(C a constant of integration)\\Ae^{\frac{t}{1500}}=300e^{\frac{t}{1500}}+C\\$Divide all through by e^{\frac{t}{1500}}\\A(t)=300+Ce^{-\frac{t}{1500}}$

Recall that when t=0, A(t)=3000 (our initial condition)

$3000=300+Ce^{0}\\C=2700\\$Therefore:\\A(t)=300+2700e^{-\dfrac{t}{1500}}$

3 0

3 years ago

WILL GIVE A BRAINLEST

Gnoma [55]

Answer: "No, the triangles are not necessarily congruent." is the correct statement .

Step-by-step explanation:

In ΔCDE, m∠C = 30° and m∠E = 50°

Therefore by angle sum property of triangles

m∠C+m∠D+m∠E=180°

⇒m∠D=180°-m∠E-m∠C=180°-30°-50°=100°

⇒m∠D=100°

In ΔFGH, m∠G = 100° and m∠H = 50°

Similarly m∠F +∠G+m∠H=180°

⇒m∠F=180°-∠G-m∠H=180°-100°-50=30°

⇒m∠F=30°

Now ΔCDE and ΔFGH

m∠C=m∠F=30°,m∠D=m∠G=100°,m∠E=m∠H=50°

by AAA similarity criteria ΔCDE ≈ ΔFGH but can't say congruent.

Congruent triangles are the pair of triangles in which corresponding sides and angles are equal . A congruent triangle is a similar triangle but a similar triangle may not be a congruent triangle.

8 0

3 years ago

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