0,2x^{2} - 0,2x - 0,2x^{2} - 0,5x < 0.6x-4
21+20=8(2x-0,5)
-41/8=2x-0,5
-5.125+05=2x
-4,625=2x
x=-2,3125
но по моему там отпечатка и должно быть 21=20-8(2x-0,5)
2log0.2(9) * log9(5) = log0.2(81) * log 9 (5) = log9 (81) / log9 (0.2) * log9 (5)= 2 / log9 (1/5) * log9 (5) = 2 / [log9 1 - log9(5)] * log9(5) = 2 / [0-log9(5)] * log9(5) = 2/ (-log9(5)) * log9(5) = -2