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Step 6The quadratic equation
If none of the combinations you get (from step 4) add up right, you'll have to use the quadratic equation.
(-b +/- sqrt (b^2 - 4ac))/2a
(sqrt (#) = square root of #)
Where a trinomial has the form ax^2 + bx + c.
So, if you wanted to use the quadratic formula with 1x^2 + 3x + 2, you'd plug in like so:
(-3 +/- sqrt (3^2 - 4 (-2) (1)) / 2.
This simplifies down to (-3 +/- sqrt 17)/2. The factors of 1x^2 + 3x + 2 would be (x - ((-3 + sqrt 17)/2)) (x - ((-3 - sqrt 17)/2)). (You stick the answer to the right of an "x - ". More on why that works, in step [8].)
(-b +/- sqrt (b^2 - 4ac))/2a
(sqrt (#) = square root of #)
Where a trinomial has the form ax^2 + bx + c.
So, if you wanted to use the quadratic formula with 1x^2 + 3x + 2, you'd plug in like so:
(-3 +/- sqrt (3^2 - 4 (-2) (1)) / 2.
This simplifies down to (-3 +/- sqrt 17)/2. The factors of 1x^2 + 3x + 2 would be (x - ((-3 + sqrt 17)/2)) (x - ((-3 - sqrt 17)/2)). (You stick the answer to the right of an "x - ". More on why that works, in step [8].)
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