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12x>235
20x<405
x>235:12
x<405:20
x>19,5
x<20,2
ответ:20 мест
y'=-[x/sin^x+ctgx]/x^2=-[2x+sin2x]/2x^2sin^2x
3/8y-1/8y= -11+10; 2/8y= -1; y=(-1):2/8= -4. Ответ: y= -4.
a) (4x+4) / (3x^2+2x-1) = (4 (x+1)) / (3x^2+3x-x-1) = (4 (x+1)) / (3x (x+1) - 1 (x+1) = (4 (x+1)) / ((x+1) (3x-1)) (сокращаем (x+1)) = 4 / (3x-1)
б) (x^2-11x+24) / (x^2-64) = (x^2-3x-8x+24) / ((x-8) (x+8)) = (x (x-3) -8 (x-3)) / ((x-8) (x+8)) =((x-3) (x-8)) / ((x-8) (x+8)) (сокращаем (x-8)) = (x-3) / (x+8)