5) x =/= 5; то есть б) x = (-oo; 5) U (5; +oo)
6) Int (8x^3 + 2/x) dx = 8x^4/4 + 2*ln|x| + C = 2x^4 + 2*ln|x| + C
7) 10% от 1400 = 1400*10/100 = 1400/10 = 140
8) lim(x^2 - x + 5) = 2^2 - 2 + 5 = 4 - 2 + 5 = 7
9) z = -1 + i
tg (fi) = 1/(-1) = -1; fi = 3pi/4