Calculs Fractionnaires:

A = 3/7-2/7×21/8 | B = 5/4-2/3×9/16 | C = (2+2/3)×(4/5-2/3) | D = 1-(1/4+3/4×4/5)

Calculs & Puissances:

E = -3×(5-3×2)³ | F = (15-6×3)×(7-6-2×4)²

2
Merci aux personnes qui m'auront aidez ! :)

Réponses

2013-12-31T15:46:02+01:00
Calculs Fractionnaires:
A = 3/7-2/7×21/8
=3/7-42/56
=24/56-42/56
=-18/56
=-9/28

B = 5/4-2/3×9/16 
=5/4-18/48
=5/4-9/24
=30/24-9/24
=21/24
=7/8

C = (2+2/3)×(4/5-2/3)
=(6/3+2/3)*(12/15-10/15)
=8/3*2/15
=16/45

D = 1-(1/4+3/4×4/5)
=1-(5/20+12/20)
=20/20-17/20
=3/20

Calculs & Puissances
:
E = -3×(5-3×2)³ 
=-3*(5-6)²
=-3*(-1)²
=-3*1
=-3

F = (15-6×3)×(7-6-2×4)²
=(15-18)*(1-8)²
=-3*(-7)²
=-3*49
=-147
Pourquoi dans la E vous avez changer " ³ " en " ² "
oups, dsl j'avais pas vu, je corrige
E = -3×(5-3×2)³
=-3*(5-6)³
=-3*(-1)³
=-3*(-1)
=3
2013-12-31T15:56:44+01:00
A = 3/7-2/7×21/8
 \frac{3}{7} -  \frac{2}{7}    ×  \frac{21}{8}
 \frac{1}{7}  ×  \frac{21}{8} =  \frac{21}{56} =  \frac{3}{8}

B = 5/4-2/3×9/16
B = \frac{5}{4} -  \frac{2}{3}  ×  \frac{4}{5} -  \frac{2}{3}
B = \frac{15}{12} -  \frac{8}{12}    ×  \frac{12}{15} -  \frac{10}{15}
B =  \frac{7}{12}  ×  \frac{2}{15}
B =  \frac{14}{180}
B =  \frac{7}{90}

C = (2+2/3)×(4/5-2/3)
C = 
(  \frac{6}{3} +  \frac{2}{3}  × (\frac{12}{15} - \frac{10}{15}
C =  \frac{8}{3}  ×  \frac{2}{15}
C =  \frac{16}{45}

D = 1-(1/4+3/4×4/5)
D = 
1 - ( \frac{1}{4} + \frac{3}{4} × \frac{4}{5})
D = 1- (1 × \frac{4}{5})
D =  \frac{1}{5}
Je me suis embrouillé dans les signes !! le grand A signifie multiplié. Désolé !