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Exercice 3
Développer et réduire chacune des expressions algébriques suivantes :
1. A = x + 2(x - 5) + 8(3 – 2x)
2. B=p-2(p – 5) – 8(3 – 2p)
3. C = x(x + 5) +8(3 + 2x)
4. D = a + 2(a – 5) + 8(3 – 2a)
5. E = (5 – 2z)(z - 4)
6. F = (b – 4)2 + (36 + 1)2
7. G = (x - 1)2 – (2x + 5)2
8. H = n(n + 1)(n-3)

Svp please je suis encore collé 2 h et je n’y arrive pas merci

Sagot :

Bonjour,

1. A = x + 2(x - 5) + 8(3 – 2x)

= x+2x -10 +24 -16x

= -13x =14

2. B=p-2(p – 5) – 8(3 – 2p)

= p-2p +10 -24 +16p

= 15p -14

3. C = x(x + 5) +8(3 + 2x)

= x² +5x +24 +16x

=x² =21x +24

4. D = a + 2(a – 5) + 8(3 – 2a)

= a+2a² -10 +24 -16a

=2a²  -15a +14

5. E = (5 – 2z)(z - 4)

= 5z -20 -2z² +8z

= -2z² +13z -20

6. F = (b – 4)² + (36 + 1)²

= b² -8b +16 +37²

= b² -8b +16 +1 369

= b² -8b + 1 385

7. G = (x - 1)² – (2x + 5)²

= x² -2x +1 -(4x² +20x +25)

=x² -2x +1 -4x² -20x-25

= -3x² -22x -24

8. H = n(n + 1)(n-3)

= (n² +n) (n-3)

= n³ -3n² +n² -3n

= n³ -2n² -3n