Q. Write the equation in standard form for the circle x2+y2−4x+7=0.
Identify equation and need: Identify the given equation and the need to complete the square for x.The given equation is x2+y2−4x+7=0. To get it into standard form, we need to complete the square for the x terms.
Group and leave space: Group the x terms and leave a space for completing the square.x2−4x+()+y2=−7We will add a certain number inside the parentheses to complete the square for the x terms.
Calculate number to complete: Calculate the number needed to complete the square for the x terms.To complete the square, we take the coefficient of x, which is −4, divide it by 2, and square it. (−4/2)2=4.Add 4 inside the parentheses to complete the square for the x terms.
Add number to both sides: Add the same number to both sides of the equation to maintain equality.x2−4x+4+y2=−7+4Now the equation is balanced.
Factor and simplify: Factor the completed square for the x terms and simplify the right side of the equation.(x−2)2+y2=−3This is the equation with the x terms factored.
Ensure positive right side: Since the standard form of a circle's equation is (x−h)2+(y−k)2=r2, we need to ensure the right side of the equation is positive because the radius squared must be a positive number.However, we have a negative number on the right side, which indicates a math error. A circle cannot have a negative radius squared.
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