Q. Write the equation in standard form for the circle x2+y2−6y−9=0.
Identify equation and need: Identify the given equation and the need to complete the square for y.The given equation is x2+y2−6y−9=0. To get it into standard form, we need to complete the square for the y terms.
Group and leave space: Group the y terms and leave a space to complete the square.x2+(y2−6y+__)−9=0+__We will determine the number to fill in the blanks that completes the square for the y terms.
Calculate number to complete: Calculate the number needed to complete the square for y.To complete the square, we take half of the coefficient of y, which is −6, divide it by 2 to get −3, and then square it to get 9. This is the number we add to both sides of the equation.
Add number to complete: Add the number to complete the square on both sides of the equation.x2+(y2−6y+9)−9=0+9Now the equation looks like this:x2+(y−3)2−9+9=0+9
Simplify equation: Simplify the equation. x2+(y−3)2=9 This is the standard form of the circle's equation.
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