A) f(-1) = 5 + 3 - 1 = 7
б) 5x^2 - 3x - 1 = 1
5x^2 - 3x - 2 = 0
D = 9 + 40 = 49
x1 = 3 - 7 /10 = -0.4
x2 = 10/10 = 1
в) 5 * 0 - 3 * 0 - 1 = -1 ( да, равенство выполняется)
f(x) = -3x + 9
-3x + 9 < 0
-3x + 9 = 0
-3x = -9
x = 3
-(+)--(3)-(-)-->
(3;+00)
б) -3х + 9 = 0
х = 3
f(x) = (x+1)/x^2 - 4
x^2 - 4 = 0
(x-2)(x+2) = 0
x = 2
x = -2
D(f) = (-00;-2)U(-2;2)U(2;+00)