挽一下

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x=linspace(-2,2,500);\\
y1=x-cos(x);\\
plot(x,y1,':');\\
hold on;\\
y2=(x.$\wedge$3)/3-x;\\
plot(x,y2,'-');\\

x=solve('x-cos(x)')\\
x = 0.73908513321516064165531208767387\\
x=solve('(x$\wedge$3)/3-x')\\
x = 0\\
3$\wedge$(1/2)\\
-3$\wedge$(1/2)\\

x=1:1:24;\\
y=$[$14 14 14 14 15 16 18 20 22 23 25 28 31 32 31 29 27 25 24 22 20 18 17 16$]$;\\
a=polyfit(x,y,3)\\
a = -0.0070\quad 0.1528\quad 0.3922\quad 11.6304\\
b=polyfit(x,y,4)\\
b = 0.0011\quad -0.0629\quad 1.0643\quad -4.9203\quad 19.4817\\
y1=a(1)*x.$\wedge$3+a(2)*x.$\wedge$2+a(3)*x+a(4);\\
y2=b(1)*x.$\wedge$4+b(2)*x.$\wedge$3+b(3)*x.$\wedge$2+b(4)*x+b(5);\\
plot(x,y,'*',x,y1,':',x,y2,'-')\\

求三四题