F' = 9*8 X^7 - 8*7X^6 + 4
<span>y' = tg' x + ctg' x = 1/(cos^2 (x) ) + (- 1/(sin^2 (x) ) = 1/(cos^2 (x) ) - 1/(sin^2 (x) ) = 1/(sin^2 (x) * cos^2 (x) ) = [(1-cos(2x))/2 ]*[(1+cos(2x))/2] = (1-cos^2 (2x) )/4</span>
+ - +
________₀_________₀_________
- 3 1
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Ответ : x ∈ (- ∞ ; - 3) ∪ (1 ; + ∞)