Exercices sur le chapitre 7 : calcul littéral
Calcul mental
1/ –5–8=–13 2/ –9×–5=45 3/ –38=5 4/ 6×–7=–42 5/ 8–14=–6
6/ –7×8=–56 7/ 9–18=–9 8/ –1–1=–2 9/ –12×3=–36 10/ –1–2–3=–6
Exercice 1 page 114 a/
A=6x3x A=9x D=5x3 D=impossible
G=9x24x2 G=13x2
B=82x
B=on ne peut pas ! E=4x22x2 E=6x2 H=7x23x2 H=10x2
C=4x5x C=9x F=5x4x2 F=impossible I=9x2x2 I=10x2
b/
J=5–9x J=pas possible
M=–8x2x M=–6x R=–5x2–7x R=pas possible
K=5x –7x K=–2x N=–8x2–6x2 N=–14x2 S=4x2–6x2 S=–2x2
L=–3x –6x L=–9x P=43x2 P=pas possible
T=–5x2– x2 T=–6x2 Exercice 2 page 114
A=5a29a A=14a2 B=8a6a3a B=17a
C=73a4a C=77a
D=6a28a23a2 D=17a2
E=5a246a2 E=11a24 F=5a4a25a2 F=5a9a2
G=8m –10m4m G=12m –10m G=2m
H=5m –4m8m H=9m
I=–8m –2m –5m I=–15m
J=6m25m2–8m2 J=11m2–8m2 J=3m2
K=2m –7m24m2 K=2m –3m2
L=–7m25m2–3m2 L=–10m2
M=2n25n –46n227 M=2n26n2 27–4 5n M=8n2 5 5n
N=–8n27–3n4n2–2n –5 N=–8n24n2 –3n –2n 7–5 N=–4n2 –5n 2
R=–9n2–54–7n22n –8n R=–9n2–7n2 2n –8n –54 R=–16n2–6n –1
S=53n –4n28n24n –5 S=–4n28n2 3n4n 5–5 S=4n2 7n
Exercice 4 page 114 a/
A=7×3x A=21x D=4x×3 D=12x
B=5x×2x B=10x2 E=2x2×4 E=8x2
C=6×3x2 C=18x2 F=6x×2x F=12x2 b/
G=–3x×5x G=–15x2 J=–2x–8x J=16x2 M=–4–3x2 M=12x2
H=–7×2x H=–14x K=2–5x2 K=–10x2 N=4x2–5
N=–20x2
I=3x–4x I=–12x2 L=–6x2×2 L=–12x2 P=–2x×8x P=–16x2
Exercice 5 page 114 a/
A=73x
A=pas possible B=7×3B=21x x
C=7x×3x C=21x2
D=7x3x D=10x
b/
E=–5×2x E=–10x
F=–6x –2x F=–8x
G=–3x–2x G=6x2
H=–82x H=pas possible
Exercice 6 page 114
• 5x=9x ; 6×=–12x2 5x4x=9x ; 6×–2x2=–12x2
• ….–4x=7x ; –3x=–18x2 11x –4x=7x ; –3x6x=–18x2
• 7=–28x2 ; –8x=–12x 7–4x2=–28x2 ; –4x –8x=–12x
Correction n°9 a/ page 114 A=52x7
A=5×2x5×7 A=10x35
C=x3x7
C=x×3xx×7 C=3x27x
B=52x×3 B=3×53×2x B=156x
D=4x2x6
D=4x×2x4x×6 D=8x224x
Exercices donnés en classe : développement simple
A=–3x4x –2 B=4x–5x9 C=–7x–3x –40
D=–4x6×–5 E=8–9x×3x F=–9x –8×–7x
F=–7x×–9x–7x×–8 F=63x256x
G=– x5x –6
G=– x×5x – x×–6
G=–5x26x
H=x1– x
H=x×1 x×– x H=x – x2
I=7x–5x3
On ne distribue pas ! Il faudra faire autre chose...
Calcul mental 1/ –5×–7=35 2/ 3×–9=–27 3/ 8×–7=–56 4/ –1×–1=1 5/ 6×7=42
6/ –3x×x=–3x2 7/ – x×–5x=5x2 8/ 7×–6x=–42x 9/ 8x×–9x=–72x2 10/ –7x×–4x=28x2
Exercices sur « signe – ou + devant une paire de parenthèses »
A=–7x5––5x8 B=–5x –3–7x –9
C=8x –8–x –9 D=– x –17– x
Calcul mental 1/ –83= 2/ –1–1= 3/ 2–3= 4/ –5–9= 5/ –813=
6/ –2x5x= 7/ – x5x= 8/ 7x –15x= 9/ –5x2–8x2= 10/ 22x –7=
Exercice 14 page 115 A=3x45x2
A=3x×5x3x×24×5x4×2 A=15x26x20x8
A=15x226x8
C=4x5 32x
C=4x×34x×2x 5×35×2x C=12x8x21510x
C=8x222x15
E=5x34–2x
E=5x3×43×–2x
E=5x12−6x E=–1x12
B=52x3x7
B=5×3x5×72x×3x2x×7 B=15x356x214x
B=6x229x35
D=5x342x
D=5x×45x×2x3×43×2x D=20x10x2126x
D=10x226x12
F=7x27x2
F=7x×7x7x×2 2×7x2×2 F=49x214x14x4
F=49x228x4
Calcul mental (à l'écrit) 1/ –8x×5x=–40x2 2/ –9x –5x=–14x2 3/ 3x2–9x2=–6x2
4/ –3x–8=–3x×–8=24x 5/ –12x16x=4x
6/ –9x–8x=72x2 7/ 7x – x=7x –1x=6x 8/ 8x×– x=–8x2
9/ – x×– x=–1x×–1x=1x2=x2 10/ – x2x=1x=x
Développement double plus complexe A=–2x7–85x
A=–2x×–8–2x×5x7×–87×5x A=16x –10x2–5635x
A –10x251x –56
A'=–5x6–98x
A'=–5x×–9–5x×8x 6×–96×8x A'=45x –40x2–5448x
A'=–40x293x –54
B=–7–3x–8x5
…
B=24x241x –35
C=– x –1x11
…
C=– x2–12x –11
Correction : n°15 page 115 A=5x26x4
A=5x×6x 5x×4 2×6x 2×4 A=30x2 20x 12x 8
A=30x2 32x 8 B=–5x –3–4x –2
B=–5x×–4x –5x×–2 –3×–4x –3×–2
B=20x2 10x 12x 6 B=20x2 22x 6
Calcul mental
1/ –3x –5x=–8x 2/ 2x×–4x=–8x2 3/ 7x –10x=–3x 4/ –5×3x=–15x 5/ 5x2–7x2=–2x2 6/ –6x×–3x=18x2 7/ 7x – x=6x
8/ – x×– x=–1x×–1x=x2 9/ –5x2×–4=20x2
10/ 2xx –5=2x2–10x
Encore des développements doubles A=–5x9–83x
…
A=–15x267x –72 B=–5– x5x7
…
B=–5x2–32x –35
Exercices du mardi 15 mars Factorise :
• 16x2–3x=x×16xx×–3=x16x –3
• 21–3x=3×73×– x=37– x
• 4y2–6=2×2y²2×−3=22y2–3
• 3x2x=x×3xx×1=x3x1
De même avec :
• A=3x2–7x=x×3xx×–7=x3x –7
• B=36x –6=6×6x –6×1=66x –1
• C=y2–12y=yy−12
• D=12x –6x2=x12–6x
ou D=62x – x2 ou encore D=6x2−x
• E=3xy – y2=y×3xy×– y=y3x – y