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natali 33 [55]
3 years ago
12

3x - y = 7

Mathematics
1 answer:
nataly862011 [7]3 years ago
6 0
3x - y = 7
6x - y = 10

if you subtract the second equation from the first to eliminate y you get:
3x-y-(6x-y)=7-10
3x-y-6x+y=-3
-3x=-3

so option C) -3x=-3 is the solution

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Sam has $440 in $20, $10, and $5 dollar bills. The number of twenties, tens and fives are consecutive integers in this order. Ho
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Answer: There are 12 bills for $20, 13 bills for $10 and 14 bills for $5.

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Let the number of tens be x+1

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Write the standard equation of a circle with center (0,3) and radius 7
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The graph below shows the rate that water leaves a tank, in gallons per hour, where t is measured in hours. (Please give exact a
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Answer:

Part a) 10 gallons

Part b) 4.59 hours

Step-by-step explanation:

<u><em>The picture of the question in the attached figure</em></u>

Part a) How much water left the tank during the 6 hours shown?

To find out how much water left the tank during the 6 hours, determine the area of the graph in that interval

so

Calculate the area of the rectangle plus the area of the triangle

(4)(2)+\frac{1}{2}(6-4)(2)

8+2=10\ gal

Part b) How many hours did it take for 9 gallons to leave the tank?

we know that

In the interval [0,4]

8 gallons of water leaves the tank in 4 hours (remember that the area in that interval is equal to 8 gallons)

so

Find out in the interval (4,6] how  many hours did it take for 1 gallon to leave the tank

First determine the equation of the line in the interval (4,6)

we have the points (4,2) and (6,0)

The slope is equal to

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The equation of the line is

y=-(x-6)\\y=-x+6

Determine the area of graph in the interval (4,x) (Is the area of trapezoid)

so

A=\frac{1}{2}(2+(-x+6))((x-4)

A=\frac{1}{2}(8-x)((x-4)

A=\frac{1}{2}(-x^2+12x-32)\\\\A=-\frac{1}{2}x^{2}+6x-16

For A=1 gal

1=-\frac{1}{2}x^{2}+6x-16

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solve the quadratic equation by graphing

The solution is x=4.59 hours

see the attached figure N 2

3 0
3 years ago
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