Q. x2+y2+6x−4y=3A circle in the xy-plane has the equation shown. What is the y coordinate of the center of the circle?
Rewriting the equation: To find the center of the circle, we need to rewrite the equation in the standard form of a circle, which is (x−h)2+(y−k)2=r2, where (h,k) is the center of the circle. We will complete the square for both x and y.
Grouping the terms: First, we group the x terms and the y terms together: (x2+6x)+(y2−4y)=3.
Completing the square for terms: To complete the square for the terms, we take half of the coefficient of , which is , and square it, adding 333^222 = 999 to both sides of the equation.
Completing the square for y terms: Similarly, to complete the square for the y terms, we take half of the coefficient of y, which is -\frac{444}{222} = −2-2−2, and square it, adding (−2-2−2)^222 = 444 to both sides of the equation.
Adding constants to both sides: Now we add 999 and 444 to both sides of the equation to maintain equality: (x2+6x+9)+(y2−4y+4)=3+9+4(x^2 + 6x + 9) + (y^2 - 4y + 4) = 3 + 9 + 4(x2+6x+9)+(y2−4y+4)=3+9+4.
Simplifying the right side: Simplify the right side of the equation: 3+9+4=163 + 9 + 4 = 163+9+4=16.
Standard form of the equation: The equation now looks like this: (x2+6x+9)+(y2−4y+4)=16(x^2 + 6x + 9) + (y^2 - 4y + 4) = 16(x2+6x+9)+(y2−4y+4)=16.
Finding the center of the circle: We can now rewrite the equation as (x+3)2+(y−2)2=16(x + 3)^2 + (y - 2)^2 = 16(x+3)2+(y−2)2=16, which is in the standard form of a circle.
The y-coordinate of the center: From the standard form (x+3)2+(y−2)2=16(x + 3)^2 + (y - 2)^2 = 16(x+3)2+(y−2)2=16, we can see that the center of the circle is at (−3,2)(-3, 2)(−3,2).
The y-coordinate of the center: From the standard form (x+3)2+(y−2)2=16(x + 3)^2 + (y - 2)^2 = 16(x+3)2+(y−2)2=16, we can see that the center of the circle is at (−3,2)(-3, 2)(−3,2).The y-coordinate of the center of the circle is 222.
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