Sagot :
1) -3(x+5)(x-1) = 0
-3x -15 = 0 x-1 = 0
-3x = 15 x = 1
x = 15/-3
x = -5
S = {-5;1}
x -∞ -5 1 +∞
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signe de
-3(x+5) - - O +
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signe de
(x-1) - O + +
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signe de
-3(x+5)(x-1) + O - O +