# 数学建模与数学实验 作业

3.
>> syms a b >> a=2.3;b=4.89; >> sqrt(a^2+b^2)/abs(a-b) ans = 2.0864

5.
>> syms x >> x=1.23; >> 'arctanx'+sqrt(log(x+1)) ans = 97.8955 114.8955 99.8955 116.8955 97.8955 110.8955 120.8955

16.
>> syms x >> limit((1/3)^(1/2*x),x,0,'right') ans = 1

21.
>> syms x y >> y=(x^2+2*x+1)/(x^2-x+2); >> limit(y,x,inf) ans = 1

23.
>> syms x y

>> y='x+tanx/1+x^2'; >> diff(y) ans = 1+2*x

24.
>> syms x y >> y='1/exp(3*x)*tanx'; >> diff(y) ans = -3/exp(3*x)*tanx

31.
>> syms x y >> y=exp(x)*sin(x)^2; >> int(y) ans = 1/5*(sin(x)-2*cos(x))*exp(x)*sin(x)+2/5*exp(x)

33.
>> syms x y >> y='(2*x-cosx)*(1/exp(x^2))'; >> int(y) ans = -1/exp(x^2)-1/2*cosx*pi^(1/2)*erf(x)

34.
>> syms x y >> y=exp(-x)*(3*x+2); >> int(y,0,1)

ans = -8*exp(-1)+5

38.
>> syms x y >> y=(x^2)*exp(-x); >> int(y,0,inf) ans = 2

11.
>> x=0:0.1:2*pi; y1=cos(3*sqrt(x)); y2=3*cos(sqrt(x)); plot(x,y1,'c-x',x,y2,'r*--')

13.
>> t=0:pi/50: 2*pi; 'x=t^2'; y=sin(t); z=t; plot3(x,y,z)

>> t=0:pi/50: 2*pi; 'x=t^2'; y=sin(t); z=t; stem3(x,y,z)

28.
>> f='(x-1)^3*x^2.5'; >> [x,y]=fminbnd(f,-1,5) x= 0.4545

y= -0.0226

29.
>> f='3*x^4-4*x^3+1'; >> [x,y]=fminbnd(f,-inf,inf) x= NaN

y= NaN

《数学建模与数学实验》课程作业