22.x is not equal to-1 and -2.

23、2n- 1

24、(- 1,5)

25. Root number 3

26. I can't see it clearly, but the semicolon above the formula =0, so it =0.

27. The original formula = (25/9) 0.5+1(0.1)-(64/27)-3+37/48 = 5/3+100-9.

If you can't see clearly, compare it and do the math yourself.

28, from f(2)=f(4), the axis of symmetry is x=3, that is, -b/2=3, so b=-6,

So f (x) = x 2-6x+c

X 2-6x+C > c-8

X 2-6x+8 > 0

That is, (x-2) (x-4) >: 0

So x < 2 or x> four.