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Setler [38]
3 years ago
8

What is the elimination of 20x+5y=120 and 10x+7.5=80

Mathematics
1 answer:
Grace [21]3 years ago
5 0
20x+5y=120
10x+7.5y=80    multiply this one by 2
___________

20x+5y=120
20x+15y=160   subtract 

___________

        -10y=-40    divide both sides by -10 
____________

             y=4         

20x+5(4)=120   plug 4 in for y in the first equation 
20x+20=120     multiply 
20x=100           subtract 
x=5                   divide to find x




 
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What is the exact value of <img src="https://tex.z-dn.net/?f=tan%5Cfrac%7B11%5Cpi%20%7D%7B12%7D" id="TexFormula1" title="tan\fra
AnnyKZ [126]

Notice that

11/12 = 1/6 + 3/4

so that

tan(11π/12) = tan(π/6 + 3π/4)

Then recalling that

sin(x + y) = sin(x) cos(y) + cos(x) sin(y)

cos(x + y) = cos(x) cos(y) - sin(x) sin(y)

⇒   tan(x + y) = (tan(x) + tan(y))/(1 - tan(x) tan(y))

it follows that

tan(11π/12) = (tan(π/6) + tan(3π/4))/(1 - tan(π/6) tan(3π/4))

tan(11π/12) = (1/√3 - 1)/(1 + 1/√3)

tan(11π/12) = (1 - √3)/(√3 + 1)

tan(11π/12) = - (√3 - 1)²/((√3 + 1) (√3 - 1))

tan(11π/12) = - (4 - 2√3)/2

tan(11π/12) = - (2 - √3) … … … [A]

8 0
2 years ago
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3 years ago
The number 16 has two square roots: 4 and
maw [93]

Answer:

4 and -4 are both the square roots of 16

Step-by-step explanation:

3 0
3 years ago
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Please help with this question I really need it right now please show work and please if you don't understand this question plea
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Answer:a is the correct option

Step-by-step explanation:

The table is divided into columns for month, sales and expense

Total number of sales for four months is determined by adding up the sales for each month. It becomes

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Total number of sales for four months is determined by adding up the expenses for each month. It becomes

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Profit or loss = total sales - total expenses

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