Question

Calculati: 5 supra 21 - 3 supra 14 + 2 supra 7 b. 9 supra 20 + 7 supra 10 - 2 supra 15 c. 11 supra 20 - deschidem paranteza 1 supra 4 + 1 supra 5 inchidem paranteza
va implor ajutatima va rog mult mult foarte mult

Answer 1

5/21-3/14+2/7= 5/21(amplificam cu 2)-3/14(×3)+2/7(×6)=10/42-9/42+12/42=13/42
21=3×7
14=2×7
7=7
-------------
c.m.m.m.c=3×2×7=42
20-(1/4+1/5)=20-(1/4(×5)+1/5(×4)=20/1(×20)-1/20=
400/20-1/20=399/20

Answer 2

5/21 - 3/14 + 2/7
= (42:21x5)/42-(42:14x3)/42 + (42:7x2)/42
= 10/42 - 9/42+ 12/42
= 13/42
b))
9/20 +7/10+2/15
= (60:20x9)/60 + (60:10x7)/60 + (60:15x2)/60
= 27/60 + 42/60 + 8/60
= 77/60
C))
11/20-(1/4+1/5)
= 11/20- [(20:4x1)/20 + ( 20:5x1)/20]
= 11/20-(5/20+4/20)
=11/20-9/20
= 2/20
= 1/10
Sper ca te-am ajutat !!