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Réponse :

Explications étape par étape :

1)

a) 5 x (3+4) = 5 x 7

b) 9 x a + 6 x b =9a + 6b

c) (7,2 -6.9) x 2,5 = 0.3 x 2,5

d) a + b + a x b = a + b + ab

e) (a + b) x (a - b) = (a + b)(a - b)

f) a x (b +c) x (x + y) = a(b + c)(x + y)

g) 2 x π x R = 2πR

h) 4 x a x b = 4ab

i) 3 x a x a x b = 3a²b

j) π x R x R = πR²

2)

[tex]A = 3*5+2=15+2=17\\B=23-4*5=23-20=3\\C=7*5-32+2*5=35-32+10=13\\D=7(5+3)=7*8=56\\E=(5+1)(5+2)=6*7=42\\F=3(4*5-12)=3(20-12)=3*8=24[/tex]