Clear[funkce]
funkce[x_] := (x^3) - 2*(x^2) + 5
Plot[funkce[t], {t, -1, 1}]

Clear[g]

a = 7

g[x_] := (Sqrt[((Sin[1 + (x/a)^2])^2 + 1)])

Plot[g[z], {z, -a, a}]

Clear[g]

Clear[a]

g[x_] := a + (x^2)

Plot[g[z], {z, -1, 1}]

Clear[g]

Clear[a]

g[x_] := a + (x^2)

Plot[g[(a^2)], {a, -1, 1}]

Clear[g]
g[x_] := Sin[x] /; Sin[x] ≥ 0
g[x_] := -Sin[x] /; Sin[x] < 0;
Plot[g[t], {t, -π, π}]

Clear[a]

Clear[g]

g[x_] := (((Abs[x]))^a) /; x + (a^2) < 1
g[x_] := 
        x /; x + (a^2) ≥ 1;
Plot[g[a], {a, -1, 5}]

?If

g[x_] := If[x + (a^2) < 1, (((Abs[x]))^a), x]

Plot[g[a], {a, -1, 5}]