Solve Quadratic Equation

Example about solving quadratic equations by factoring.

Example 1

Solve quadratic equations by first expanding and then factoring.

What are the real roots of the equation $(x+3)(x−1)=-4$?

  1. $-3$ and $1$

  2. $-7$ and $-3$

  3. $-1$

  4. $1$

  5. $3$ and $1$

Solution


  1. We first need to expand the left side of the given equation and write in quadratic standard form (left side equal to zero)

    $(x+3)(x−1)=-4$

    $x^2-x+3x-3=-4$

    $x^2+2x+1=0$

  2. We now factor the above equation

    $(x+1)^2=0$

  3. Solve for $x$

    $x=-1$

    Answer C