2c^2 - 4c - ( c^2 - 2c + 1) = 2c^2 - 4c - c^2 + 2c - 1 = c^2 - 2c - 1
Ну это же очень просто
3x^2 - 78 = 0
3x^2 = 78
X^2=26
X=✓26
(x²-9)(x²-4)≤0⇒(x-3)(x+3)(x-2)(x+2)≤0
x=-3 x=3 x=2 x=-2
+ _ + _ +
______________________
-3 -2 2 3
x∈[-3;-2] U [2;3]
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