deducir Preterite Conjugation
deducir — to deduce
The preterite of deducir is irregular, using a 'j' stem: deduje, dedujiste, dedujo.
deducir Preterite Forms
When to Use the Preterite
Use the preterite for a specific moment in the past when you reached a conclusion or when you officially deducted an amount from a payment.
Notes on deducir in the Preterite
This is a 'j-stem' irregular verb. The 'c' changes to 'j' throughout (deduj-), and it uses special endings without accents (-e, -iste, -o, etc.). Note the 'ellos' form is 'dedujeron', not 'dedujieron'.
Example Sentences
Deduje la verdad después de hablar con él.
I deduced the truth after talking to him.
yo
Él dedujo el código rápidamente.
He deduced the code quickly.
él/ella/usted
Dedujimos que era mejor cancelar el plan.
We deduced that it was better to cancel the plan.
nosotros
Ellos dedujeron el IVA del precio total.
They deducted the VAT from the total price.
ellos/ellas/ustedes
Common Mistakes
Mistake: Dedució o deducieron.
Correct: Dedujo / dedujeron.
Why: Deducir follows the 'conducir' pattern where the 'c' becomes a 'j' in the preterite stem.
Mistake: Dedujieron.
Correct: Dedujeron.
Why: After a 'j' stem in the preterite, the 'i' in the 'ieron' ending is dropped.
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Related Tenses
Present
yo: deduzco
The present tense of deducir uses a 'zc' spelling change in the yo form: yo deduzco.
Imperfect
yo: deducía
The imperfect of deducir is completely regular: deducía, deducías, deducía.
Future
yo: deduciré
The future tense of deducir is regular: deduciré, deducirás, deducirá.
Conditional
yo: deduciría
The conditional of deducir is regular: deduciría, deducirías, deduciría.
Present Subjunctive
yo: deduzca
The present subjunctive uses the 'z' from the yo form throughout: deduzca, deduzcas, deduzca.
Imperfect Subjunctive
yo: dedujera
The imperfect subjunctive uses the 'j' stem from the preterite: dedujera, dedujeras, dedujera.
Affirmative Imperative
yo: deduce
Use 'deduce' for tú and 'deduzca' for formal commands.
Negative Imperative
yo: no deduzcas
The negative imperative always uses the 'z' stem: no deduzcas, no deduzca.