Final answer:
The sentence 'Tengo una mochila amarillo.' is incorrect because the adjective 'amarillo' needs to agree in gender and number with the noun it modifies. The correct form would be 'Tengo una mochila amarilla.'
Step-by-step explanation:
The sentence 'Tengo una mochila amarillo.' is grammatically incorrect because the adjective 'amarillo' needs to agree in gender and number with the noun it modifies. Since 'mochila' is a feminine noun, the correct form of the adjective should be 'amarilla.' Therefore, the correct sentence should be 'Tengo una mochila amarilla.'
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