<span>Sin^4x+2sin^2xcos^2x+cos^4x=(sin^2x+cos^2x)^2=1^2=1</span>
4(х+5) 4
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(х+5)(х+5) х+5
Дано: арифметическая прогрессия u a₁= 2 ;d = -3 .
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S₁₀ -?
* * * S(n) =(2a₁ +(n-1)d )/2 * n . * * *
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S₁₀ =(2*2 +(10-1)*(-3) )/2 * 10 = 5(4 -27) =5*(-23) =- 115.