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Réponse :

Explications étape par étape

Bonjour

Calculer :

A = 1/a + 2/b + 3/c

B = b/a + a/b

C = a/(b + c)

D = a - c/(a + b)

a = 3 ; b = 5 ; c = 7

A = 1/3 + 2/5 + 3/7

A = 35/105 + 42/105 + 45/105

A = 122/105

B = 5/3 + 3/5

B = 25/15 + 9/15

B = 34/15

C = 3/(5 + 7)

C = 3/12

C = 1/4

D = 3 - 7/(3 + 5)

D = 3 - 7/8

D = 24/8 - 7/8

D = 17/8

a = -2 ; b = 2/5 ; c = 1

A = 1/-2 + 2/(2/5) + 3/1

A = -1/2 + 2 x 5/2 + 3

A= -1/2 + 5 + 3

A = -1/2 + 8

A = -1/2 + 16/2

A = 15/2

B = (2/5)/(-2) + (-2)/(2/5)

B = 2/5 x (-1/2) - 2 x 5/2

B = -1/5 - 5

B = -1/5 - 25/5

B = -26/5

C = 1/(2/5 + 1)

C = 1/(2/5 + 5/5)

C = 1/(7/5)

C = 1 x 5/7

C = 5/7

D = -2 - 1/(-2 + 2/5)

D = -2 - 1/(-10/5 + 2/5)

D = -2 - 1/(-8/5)

D = -2 - 1 x (-5/8)

D = -16/8 + 5/8

D = -11/8

a = 1/2 ; b = -1/3 ; c = 3/5

A = 1/(1/2) + 2/(-1/3) + 3/(3/5)

A = 2 - 6 + 3 x 5/3

A = -4 + 5

A = 1

B = (-1/3)/(1/2) + (1/2)/(-1/3)

B = -1/3 x 2 - 1/2 x 3

B = -2/3 - 3/2

B = -4/6 - 9/6

B = - 13/6

C = (1/2)/(-1/3 + 3/5)

C = 1/2 / (-5/15 + 9/15)

C = 1/2 / (4/15)

C = 1/2 x 15/4

C = 15/8

D = 1/2 - (3/5)/(1/2 + (-1/3))

D = 1/2 - 3/5 / (3/6 - 2/6)

D = 1/2 - 3/5 / (1/6)

D = 1/2 - 3/5 x 6

D = 1/2 - 18/5

D = 5/10 - 36/10

D = 31/10

a = -5/2 ; b = 5/2 ; c = -1

A = 1/(-5/2) + 2/(5/2) + 3/(-1)

A = -2/5 + 2 x 2/5 - 3

A = -2/5 + 4/5 - 15/5

A = -13/5

B = (5/2)/(-5/2) + (-5/2)/(5/2)

B = 5/2 x (-2/5) - 5/2 x 2/5

B = -1 - 1

B = -2

C = (-5/2)/(5/2 + (-1))

C = -5/2 / (5/2 - 2/2)

C = -5/2 / (3/2)

C = -5/2 x 2/3

C = -5/3

D = -5/2 - (-1)/(-5/2 + 5/2)

D = -5/2 + 1 / 0 => impossible le dénominateur ne peut pas être nul