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Sagot :

bonsoir

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

1) montrer que B(x) = (3x - 2)/(x - 1) :

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

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

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

2) Résoudre B(x) = 0 :

x - 1 # 0

x # 1

3x - 2 = 0

3x = 2

x = 2/3

3) A(x) = (x^2 + 2x - 2)/(x - 1)

a) A(11) = (11^2 + 2 * 11 - 2)/(11 - 1) = (121 + 22 - 2)/10 = (121 + 20)/10 = 141/10 = 14,1

B(11) = (3 * 11 - 2)/(11 - 1) = (33 - 2)/10 = 31/10 = 3,1

A(11) - B(11) = 14,1 - 3,1 = 11

b) montrer que A(x) - B(x) = x :

= (x^2 + 2x - 2)/(x - 1) - (3x - 2)/(x - 1)

= (x^2 + 2x - 2 - 3x + 2)/(x - 1)

= (x^2 - x)/(x - 1)

= x(x - 1)/(x - 1)

= x

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