Reversing the quadratic equation is known as factoring. The quadratic equation is written in the form of ax^2 + bx + c = 0. The factor of a quadratic is written as (x -/+ a)(x -/+ b) = 0. Writing the quadratic equation from its factored form is called FOIL (first, inner, outer, last), where you multiply the first variable in the first parentheses with the first in the second parenthesis (x^2). Multiply the inner variables in the parenthesis (ax), then the outer (bx) and, finally, the last variables in each parentheses (ab).
Instructions
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1
Write down the quadratic equation on a clean sheet of paper in the form ax^2 + bx + c = 0. Use the example of x^2 + x - 12 = 0.
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2
Find two numbers that add to +1 and multiply to -12. The answer in this case is +4 and -3.
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3
Write the factors you found in (x +/- a)(x +/- b) = 0. In this case, the answer would be written as (x + 4)(x - 3) = 0.