Q. Write the equation in standard form for the circle x2+y2+10y−25=0.
Identify equation and need: Identify the given equation and the need to complete the square for y.The given equation is x2+y2+10y−25=0. To write the equation in standard form, we need to complete the square for the y terms.
Group and leave space: Group the y terms and leave a space for completing the square.x2+(y2+10y+)−25=0We will add and subtract the same value inside the parentheses to complete the square.
Calculate value for completion: Calculate the value needed to complete the square for y.To complete the square, we take half of the coefficient of y, which is 210=5, and square it, resulting in 52=25.
Add and subtract calculated value: Add and subtract the calculated value inside the parentheses.x2+(y2+10y+25−25)−25=0Now we have the perfect square trinomial for y and an extra −25 that we will move outside the parentheses.
Write perfect square trinomial: Write the perfect square trinomial and simplify the equation.x2+(y+5)2−25−25=0Combine the constant terms on the right side.
Simplify equation: Combine the constants and write the equation in standard form. x2+(y+5)2−50=0Add 50 to both sides to get the standard form.x2+(y+5)2=50
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