6) B 7) C 8) C 9) C 10) A 11) B 12) C 13) C 14) B 15) A 16) B 17) D
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4 4\9х+1=2 17\16
40\9х+1=49\16
40\9х=49\16-1
40\9х=48\16
х=48\16:40\9
х=48\16*9\40
х=432\360
-π/6+2πk≤x≤7π/6+2π k, k∈Z
Решаем по дискриминанту
D=b^2 - 4ac
D=3^2-4*(-5)=29
x1,2 = (-b+-sqrt(D))/(2a)
x1=(-3+sqrt(29))/2
x2=(-3-sqrt(29))/2