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Hey how do you get from standard form to vertex form?

User Overactor
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1 Answer

4 votes

Step-by-step explanation:

Conversion of a quadratic equation from standard form to vertex form is done by completing the square method.

Assume the quadratic equation to be
\mathbf{ax^(2)+bx+c=0} where x is the variable.

Completing the square method is as follows:

  1. send the constant term to other side of equal
    \mathbf{ax^(2)+bx=-c}
  2. divide the whole equation be coefficient of
    \mathbf{x^(2)}, this will give
    \mathbf{x^(2)+(b)/(a)x=- (c)/(a)}
  3. add
    \mathbf{((b)/(2a))^(2)} to both side of equality
    \mathbf{x^(2)+2*(b)/(2a)x+(b)/(2a)^(2)=-(c)/(a)+(b)/(2a)^(2)}
  4. Make one fraction on the right side and compress the expression on the left side
    \mathbf{(x+(b)/(2a))^(2)=(b^(2)-4ac)/(4a^(2))}
  5. rearrange the terms will give the vertex form of standard quadratic equation
    \mathbf{a(x+(b)/(2a))^(2)-(b^(2)-4ac)/(4a)=0}

Follow the above procedure will give the vertex form.

(NOTE : you must know that
\mathbf{(x+a)^(2)=x^(2)+2ax+a^(2)}. Use this equation in transforming the equation from step 3 to step 4)

User Jack Maessen
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