සා/පෙළ ගණිතය 2019 ප්‍රශ්න පත්‍රය

Customs duty as a percentage of an item's value

පිළිතුර: Rs 540

💡 ප්‍රශ්නයේ අදහස: බද්ද යනු වටිනාකමෙන් 9% පමණි.

1. 16000 න් 1% = 60.
2. 2ගණනය: 9% = 9 × 60.
3. 39 × 60 = රු. 540.

✅ 10% = 600 නිසා 9% ටිකක් අඩු විය යුතුය: 540 ගැළපේ.

Factorise a monic trinomial

පිළිතුර: (x + 5)(x - 2)

💡 ප්‍රශ්නයේ අදහස: ගුණිතය −10 ද එකතුව 3 ද වන සංඛ්‍යා දෙකක් අවශ්‍යයි; ඒවා වරහන්වලට යයි.

1. 1−10 සඳහා යුගල: (10, −1), (−10, 1), (5, −2), (−5, 2).
2. 2එකතුව 3 වන්නේ 5 සහ −2 පමණි.
3. 3එබැවින් x² + 3x − 10 = (x + 5)(x − 2).

✅ ප්‍රසාරණය: x² − 2x + 5x − 10 = x² + 3x − 10. නිවැරදියි.

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