Example

Factoring 14x2−47x−714x^2 - 47x - 7

Factor 14x2−47x−714x^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 x⋅14xx \cdot 14x or 2x⋅7x2x \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)(14x−7)(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
(x−7)(14x+1)(x - 7)(14x + 1)14x2−97x−714x^2 - 97x - 7
(x+7)(14x−1)(x + 7)(14x - 1)14x2+97x−714x^2 + 97x - 7
(2x−7)(7x+1)(2x - 7)(7x + 1)14x2−47x−714x^2 - 47x - 7 ✓
(2x+7)(7x−1)(2x + 7)(7x - 1)14x2+47x−714x^2 + 47x - 7

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

Step 5 — Check by multiplying. (2x−7)(7x+1)=14x2+2x−49x−7=14x2−47x−7(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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