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Stella [2.4K]
3 years ago
12

A circle has the equation 2x²+12x+2y²−16y−150=0.

Mathematics
1 answer:
KonstantinChe [14]3 years ago
8 0

Answer: B. The coordinates of the center are (-3,4), and the length of the radius is 10 units.

Step-by-step explanation:

The equation of a circle in the center-radius form is:

(x-h)^{2} +(y-k)^{2}=r^{2} (1)

Where (h,k) are the coordinates of the center and r is the radius.

Now, we are given the equation of this circle as follows:

2x^{2}+12x+2y^{2}-16y-150=0 (2)

And we have to write it in the format of equation (1). So, let's begin by applying common factor 2 in the left side of the equation:

2(x^{2}+6x+y^{2}-8y-75)=0 (3)

Rearranging the equation:

x^{2}+6x+y^{2}-8y=75 (4)

(x^{2}+6x)+(y^{2}-8y)=75 (5)

Now we have to complete the square in both parenthesis, in order to have a perfect square trinomial in the form of (a\pm b)^{2}=a^{2}\pm+2ab+b^{2}:

<u>For the first parenthesis:</u>

x^{2}+6x+b^{2}

We can rewrite this as:

x^{2}+2(3)x+b^{2}

Hence in this case b=3 and b^{2}=9:

x^{2}+2(3)x+3^{2}=x^{2}+6x+9=(x+3)^{2}

<u>For the second parenthesis:</u>

y^{2}-8y+b^{2}

We can rewrite this as:

y^{2}-2(4)y+b^{2}

Hence in this case b=-3 and b^{2}=9:

y^{2}-2(4)y+4^{2}=y^{2}-8y+16=(y-4)^{2}

Then, equation (5) is rewritten as follows:

(x^{2}+6x+9)+(y^{2}-8y+16)=75+9+16 (6)

<u>Note we are adding 9 and 16 in both sides of the equation in order to keep the equality.</u>

Rearranging:

(x-3)^{2}+(y-4)^{2}=100 (7)

At this point we have the circle equation in the center radius form (x-h)^{2} +(y-k)^{2}=r^{2}

Hence:

h=-3

k=4

r=\sqrt{100}=10

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Explanation:

To find the density, the first step is to convert the weight (mass) and the volume into the appropriate units.

The volume is 8.5 gallons and this needs to be converted to litters. In this case, multiply the volume in gallons by 3.785 because each gallon contains 3.785 liters.

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Which is an equation of the line passing through (-2, 3) and perpendicular to the line 5x - y = 12?
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Answer:

An equation of the line passing through (-2, 3) and perpendicular to the line 5x - y = 12 will be:

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Step-by-step explanation:

Given the equation

5x - y = 12

converting the line into the slope-intercept form y = mx+b, where m is the slope

-y = 12-5x

y = 5x-12

The slope of the line = m = 5

We know that a line perpendicular to another line contains a slope that is the negative reciprocal of the slope of the other line, such as:

Therefore, the slope of new line = – 1/m = -1/5 = -1/5

Using the point-slope form of the line equation

y-y_1=m\left(x-x_1\right)

where m is the slope of the line and (x₁, y₁) is the point

substituting the slope of new line = -1/5 and (-2, 3)

y-y_1=m\left(x-x_1\right)

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Add 3 to both sides

y-3+3=-\frac{1}{5}\left(x+2\right)+3

y=-\frac{1}{5}x+\frac{13}{5}

Therefore, an equation of the line passing through (-2, 3) and perpendicular to the line 5x - y = 12 will be:

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Step-by-step explanation:

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