Page 1/ 3 identités remarquables - Classe de 3e Corrigé de l’exercice 1 Dévelop

Page 1/ 3 identités remarquables - Classe de 3e Corrigé de l’exercice 1 Développer chacune des expressions littérales suivantes : A = (3 x + 4)2 A = (3 x)2 + 2 × 3 x × 4 + 42 A = 9 x2 + 24 x + 16 B = (10 x + 7) × (10 x −7) B = (10 x)2 −72 B = 100 x2 −49 C = (2 x + 10) × (10 x −2) C = 2 x × 10 x + 2 x × (−2) + 10 × 10 x + 10 × (−2) C = 20 x2 −4 x + 100 x −20 C = 20 x2 + (−4 + 100) x −20 C = 20 x2 + 96 x −20 D = (x −3)2 D = x2 −2 × x × 3 + 32 D = x2 −6 x + 9 E = 7 6 x + 10 9 2 E = 7 6 x 2 + 2 × 7 6 x × 10 9 + 10 9 2 E = 49 36 x2 + 70 ×  2 27 ×  2 x + 100 81 E = 49 36 x2 + 70 27 x + 100 81 F = −(6 x −7) × (6 x + 7) F = −  (6 x)2 −72 F = − 36 x2 −49  F = −36 x2 + 49 Corrigé de l’exercice 2 Développer chacune des expressions littérales suivantes : A = (9 x + 4)2 A = (9 x)2 + 2 × 9 x × 4 + 42 A = 81 x2 + 72 x + 16 B = (6 x −9)2 B = (6 x)2 −2 × 6 x × 9 + 92 B = 36 x2 −108 x + 81 C = (2 x −1) × (x + 2) C = 2 x × x + 2 x × 2 −1 × x −1 × 2 C = 2 x2 + 4 x −x −2 C = 2 x2 + (4 −1) x −2 C = 2 x2 + 3 x −2 D = (2 x + 9) × (2 x −9) D = (2 x)2 −92 D = 4 x2 −81 E = 3 8 x −2 3  × 2 3 x + 3 8  E = 3 8 x × 2 3 x + 3 8 x × 3 8 −2 3 × 2 3 x −2 3 × 3 8 E = 1 ×  6 4 ×  6 x2 + 9 64 x −4 9 x −1 ×  6 4 ×  6 E = 1 ×  6 4 ×  6 x2 +  9 64 −4 9  x −1 ×  6 4 ×  6 E = 1 4 x2 +  9×9 64×9 −4×64 9×64  x −1 4 E = 1 4 x2 +  81 576 −256 576  x −1 4 E = 1 4 x2 −175 576 x −1 4 F = −(10 x + 1)2 F = −  (10 x)2 + 2 × 10 x × 1 + 12 F = − 100 x2 + 20 x + 1  F = −100 x2 −20 x −1 Corrigé de l’exercice 3 Développer chacune des expressions littérales suivantes : Année 2014/2015 Page 2/ 3 identités remarquables - Classe de 3e A = (x −3) × (3 x + 1) A = x × 3 x + x × 1 −3 × 3 x −3 × 1 A = 3 x2 + x −9 x −3 A = 3 x2 + (1 −9) x −3 A = 3 x2 −8 x −3 B = (9 x −6)2 B = (9 x)2 −2 × 9 x × 6 + 62 B = 81 x2 −108 x + 36 C = (9 x + 3) × (9 x −3) C = (9 x)2 −32 C = 81 x2 −9 D = (6 x + 10)2 D = (6 x)2 + 2 × 6 x × 10 + 102 D = 36 x2 + 120 x + 100 E = −(10 x + 5)2 E = −  (10 x)2 + 2 × 10 x × 5 + 52 E = − 100 x2 + 100 x + 25  E = −100 x2 −100 x −25 F = 1 7 x −9 10 2 F = 1 7 x 2 −2 × 1 7 x × 9 10 +  9 10 2 F = 1 49 x2 −9 ×  2 35 ×  2 x + 81 100 F = 1 49 x2 −9 35 x + 81 100 Corrigé de l’exercice 4 Développer chacune des expressions littérales suivantes : A = (5 x + 4)2 A = (5 x)2 + 2 × 5 x × 4 + 42 A = 25 x2 + 40 x + 16 B = (6 x −3)2 B = (6 x)2 −2 × 6 x × 3 + 32 B = 36 x2 −36 x + 9 C = (x −8) × (x + 8) C = x2 −82 C = x2 −64 D = (6 x −3) × (3 x + 6) D = 6 x × 3 x + 6 x × 6 −3 × 3 x −3 × 6 D = 18 x2 + 36 x −9 x −18 D = 18 x2 + (36 −9) x −18 D = 18 x2 + 27 x −18 E = −(5 x + 7)2 E = −  (5 x)2 + 2 × 5 x × 7 + 72 E = − 25 x2 + 70 x + 49  E = −25 x2 −70 x −49 F = 4 3 x −1 8  × 4 3 x + 1 8  F = 4 3 x 2 − 1 8 2 F = 16 9 x2 −1 64 Corrigé de l’exercice 5 Développer chacune des expressions littérales suivantes : A = (6 x −1)2 A = (6 x)2 −2 × 6 x × 1 + 12 A = 36 x2 −12 x + 1 B = (6 x + 10)2 B = (6 x)2 + 2 × 6 x × 10 + 102 B = 36 x2 + 120 x + 100 C = (9 x −2) × (9 x + 2) C = (9 x)2 −22 C = 81 x2 −4 D = (7 x + 7) × (7 x −7) Année 2014/2015 Page 3/ 3 identités remarquables - Classe de 3e D = (7 x)2 −72 D = 49 x2 −49 E =  7 x + 5 4  ×  7 x −5 4  E = (7 x)2 − 5 4 2 E = 49 x2 −25 16 F = −(3 x −8) × (8 x + 3) F = −(3 x × 8 x + 3 x × 3 −8 × 8 x −8 × 3) F = − 24 x2 + 9 x −64 x −24  F = − 24 x2 + (9 −64) x −24  F = − 24 x2 −55 x −24  F = −24 x2 + 55 x + 24 Corrigé de l’exercice 6 Développer chacune des expressions littérales suivantes : A = (2 x −8) × (8 x + 2) A = 2 x × 8 x + 2 x × 2 −8 × 8 x −8 × 2 A = 16 x2 + 4 x −64 x −16 A = 16 x2 + (4 −64) x −16 A = 16 x2 −60 x −16 B = (x + 9)2 B = x2 + 2 × x × 9 + 92 B = x2 + 18 x + 81 C = (7 x −8) × (7 x + 8) C = (7 x)2 −82 C = 49 x2 −64 D = (3 x −7)2 D = (3 x)2 −2 × 3 x × 7 + 72 D = 9 x2 −42 x + 49 E = −(9 x −10) × (9 x + 10) E = −  (9 x)2 −102 E = − 81 x2 −100  E = −81 x2 + 100 F = 4 5 x + 1 3  × 1 3 x −4 5  F = 4 5 x× 1 3 x+ 4 5 x×  −4 5  + 1 3 × 1 3 x+ 1 3 ×  −4 5  F = 4 15 x2 −16 25 x + 1 9 x −4 15 F = 4 15 x2 + −16 25 + 1 9  x −4 15 F = 4 15 x2 + −16×9 25×9 + 1×25 9×25  x −4 15 F = 4 15 x2 + −144 225 + 25 225  x −4 15 F = 4 15 x2 −119 225 x −4 15 Année 2014/2015 uploads/s3/ identites-remarquables-corrige-serie-d-exercices-2 1 .pdf

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