Question

7supra lui9 -5 supra lui 12 Calculati efectuind proba prin scadere

Answer 1

$\dfrac{7}{9}-\dfrac{5}{12}=\dfrac{28-15}{36}=\dfrac{13}{36}$

Proba:

$\dfrac{7}{9}$- $\dfrac{13}{36}$= $\dfrac{28-13}{36}$= $\dfrac{15}{36}$= $\dfrac{5}{12}$

Answer 2

7/9 - 5/12 = 

→ ca sa scazi fractiile trebuie sa le aduci la acelasi numitor;

9 = 3²
12 = 3 ×2²
cmmmc al numerelor ( 9, 12) = 3²×2²= 36

→amplific prima fractie cu 4, iar a doua fractie cu 3 

7/9 - 5/12 = ( 4 x 7 ) / ( 4 x 9 ) - ( 3 x 5 ) / ( 3 x 12) = 28/36 - 15/36 = 13/36 

Proba prin scadere:

7/9 - 13/36 = 28/36 - 13/36 = 15/36 = 5/12