Example

Factoring 14x247x714x^2 - 47x - 7

Factor 14x247x714x^2 - 47x - 7 completely using the trial and error method.

Step 1 — Write in descending order. The trinomial is already in descending order.

Step 2 — Find factor pairs of the first term. The term 14x214x^2 can be factored as x14xx \cdot 14x or 2x7x2x \cdot 7x.

Step 3 — Find factor pairs of the last term and consider signs. The last term 7-7 is negative, so its factors must have opposite signs: 1,71, -7 and 1,7-1, 7.

Step 4 — Test all combinations. Combining each pair of first-term factors with each pair of last-term factors produces eight trial factorizations. Since the original trinomial has no greatest common factor (GCF), any trial binomial containing a common factor (e.g., (x+1)(14x7)(x + 1)(14x - 7) contains a common factor of 7) can be eliminated immediately. Testing the remaining four combinations for the correct middle term (47x-47x):

Possible factorsProduct
(x7)(14x+1)(x - 7)(14x + 1)14x297x714x^2 - 97x - 7
(x+7)(14x1)(x + 7)(14x - 1)14x2+97x714x^2 + 97x - 7
(2x7)(7x+1)(2x - 7)(7x + 1)14x247x714x^2 - 47x - 7
(2x+7)(7x1)(2x + 7)(7x - 1)14x2+47x714x^2 + 47x - 7

The correct factors are (2x7)(7x+1)(2x - 7)(7x + 1).

Step 5 — Check by multiplying. (2x7)(7x+1)=14x2+2x49x7=14x247x7(2x - 7)(7x + 1) = 14x^2 + 2x - 49x - 7 = 14x^2 - 47x - 7

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Updated 2026-06-28

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