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4 years ago

2x-y=4 and 7x+3y=27 step by step

Mathematics

1 answer:

aalyn [17]4 years ago

4 0

Answer:

x=3 y=2

Step-by-step explanation:

2x-y=4

7x+3y=27

Multiply the first equation by 3

3(2x-y)=4*3

6x - 3y+12

Add this to the second equation to eliminate y

6x -3y = 12

7x+3y=27

---------------------

13x +0y = 39

Divide each side by 13

13x/13 = 39/13

x = 3

Now find y

2x-y =4

2(3) -y = 4

6-y=4

Subtract 6 from each side

6-y-6 = 4-6

-y = -2

y=2

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Since we require I, making I subject of the formula, we have

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Substituting the values of the variables into the equation, we have

$I = I_{0} 10^{\frac{dB}{10} }\\I = 10^{-12} 10^{\frac{156}{10} }\\I = 10^{-12} 10^{15.6}\\I = 10^{15.6-12} \\I = 10^{3.6} W/m^{2}$

I = 3981.072W/m²

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So, the intensity of sound which the decibel level of the sound measures 156 is 3.981 × 10³ W/m²

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