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krok68 [10]
3 years ago
15

Solve by addition ANSWER NOW

Mathematics
1 answer:
emmasim [6.3K]3 years ago
5 0
Using elimination, we add the equations, but this time from left to right. This process wants to elimination a variable. So 2x plus -2x equals 0. Moving on the next variable, 6y plus -y is 5y. On to the last variable, 18 plus 12 is 30. So we have this equation, 5y=30. 30/5 is 6, so y=6. We plug 6 into y in one of the equations you choose. In this case, I'm going to use the first equation. Plugging 6, we have this equation, 2x plus 36 is 18. 18-36 is -18. We then have this equation, 2x=-18. We know -9 times 2 is -18, so our x value is -9, So, our y=6, and our x=-9.
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(THIS IS A TEST I NEED HELP)
Leya [2.2K]

Answer:

Option (B)

Step-by-step explanation:

Length of PR = 4

RS = 4

QS = 4

For the length of PT,

PT² = RT² + PR² [Since, PT is the diagonal of rectangle PRT]

PT² = QS² + PR² [Since, RT ≅ QS]

PT² = 4² + 7²

PT² = 16 + 49

PT² = 65

Now for the length of PQ,

PQ² = QT² + PT²

PQ² = RS² + PT² [Since, QT ≅ RS]

PQ² = 4² + 65

PQ² = 16 + 65

PQ = √81

PQ = 9

Therefore, length of diagonal PQ is 9 units.

Option (B) will be the answer.

4 0
3 years ago
The area of a rectangular wall of a barn is 64 square feet. Its length is 8 feet longer than twice its width. Find the length an
ValentinkaMS [17]
L×w=64 ft^2...(1)
2w+8= l...(2)

l=64-w...(1a)

2w+8= 64-w
2w+w+8=64
3w=64-8
3w÷3= 56÷3
w=18.6'

l×w= 64
l×18.6= 64
l= 64÷18.6
l= 3.44 to the nearest hundredths.
6 0
3 years ago
Read 2 more answers
A light bulb of 200W emits 1.5μm.How many photons are emmited per second.​
Vinvika [58]

Answer:

Step-by-step explanation:

An incandescent light bulb filament is approximated by a black body radiator, and in the case of a 60W bulb the filament temperature is around 2500˚C which is 2870˚K.

There are a couple of standard black body results that we can use. Firstly the total irradiance emitted per unit area of black body is equal to:

Ed=σT4

where σ=5.67×10−8 Wm−2K−4 is the Stephan-Boltzmann constant. For our bulb we get:

Ed=5.67×10−8⋅28704=3.85×106 Wm−2

As this is a 60W bulb then it has a total irradiance of 60W. Therefore the equivalent black body surface area is:

603.85×106=1.56×10−5 m2

which is 15.6mm2 of filament area.

Secondly we have that the total number of photons emitted per second per unit area of black body is equal to:[1]

Qd=σQT3

where σQ=1.52×1015 photons.sec−1m−2K−3. For our bulb this is:

Qd=1.52×1015⋅28703=3.59×1025 photons.sec−1m−2

Multiplying by the bulb’s equivalent black body surface area gives the result we require:

3.59×1025⋅1.56×10−5=5.6×1020 photons/sec

As a sanity check we know that these photons have a total energy of 60 joules per second, so the average energy per photon is:

605.6×1020=1.1×10−19 joules

A photon of wavelength λ has energy E=hcλ, and so the average energy corresponds with a photon of wavelength:

λ=hc1.1×10−19=1.9μm

Here’s a chart of the power distribution by wavelength, with the average photon wavelength shown as the dashed line, and visible wavelengths highlighted:

emember that there are a higher proportion of photons for the longer, lower energy wavelengths, so the average is weighted to the right.

We can also see from the original calculation that the general case is:

QdWEd=σQT3WσT4=2.68×1022WT photons/sec

for a bulb of wattage W watts and filament temperature T ˚K. So the photon emission rate is inversely proportional to the filament temperature. As a somewhat counter-intuitive example, a 60W halogen bulb with 3200˚K filament only emits photons at 90% of the rate of the standard 60W bulb, despite being visibly brighter.

The reason is that as the temperature increases then an increased proportion of shorter wavelength photos are emitted and therefore the average energy per photon increases, decreasing the number emitted per second. However at the same time an increased proportion of the photons are visible rather than infra-red, making the bulb appear brighter. Here’s the power distribution chart with the 60W halogen curve added for comparison:

3 0
3 years ago
Determine the value of x
Lelechka [254]

Answer: 116 Degrees

Step-by-step explanation:

540 is what the pentagon equals! You add up all of the sides, the square equals 90 degrees because it's a right angle. 121+115+98+90 equals 424. You subtract 540 - 424 and you get 116, which is x! Good luck!

6 0
2 years ago
Find an equation of variation where y varies directly as x and y = 2 when x = 10, find y when x = -25.
Eddi Din [679]

Answer:

y = ⅕x; -5

Step-by-step explanation:

y = kx

k = y/x     Divided both sides by x

k = 2/10

k = ⅕

y = ⅕x

The equation of variation is y = ⅕x.

If x = -25,

y = ⅕(-25) = -5

4 0
3 years ago
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