设二次函数f(x)=(k减4)x^2+kx (k属于R) 对任意实数x,f(x)小于等于6x+2恒成立,数列{an}满足an+1=f(an) ...设二次函数f(x)=(k减4)x^2+kx (k属于R) 对任意实数x,f(x)小于等于6x+2恒成立,数列{an}满足an+1=f(an) (1)求函
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![设二次函数f(x)=(k减4)x^2+kx (k属于R) 对任意实数x,f(x)小于等于6x+2恒成立,数列{an}满足an+1=f(an) ...设二次函数f(x)=(k减4)x^2+kx (k属于R) 对任意实数x,f(x)小于等于6x+2恒成立,数列{an}满足an+1=f(an) (1)求函](/uploads/image/z/5088722-50-2.jpg?t=%E8%AE%BE%E4%BA%8C%E6%AC%A1%E5%87%BD%E6%95%B0f%28x%29%3D%28k%E5%87%8F4%29x%5E2%2Bkx+%28k%E5%B1%9E%E4%BA%8ER%29+%E5%AF%B9%E4%BB%BB%E6%84%8F%E5%AE%9E%E6%95%B0x%2Cf%28x%29%E5%B0%8F%E4%BA%8E%E7%AD%89%E4%BA%8E6x%2B2%E6%81%92%E6%88%90%E7%AB%8B%2C%E6%95%B0%E5%88%97%7Ban%7D%E6%BB%A1%E8%B6%B3an%2B1%3Df%28an%29+...%E8%AE%BE%E4%BA%8C%E6%AC%A1%E5%87%BD%E6%95%B0f%28x%29%3D%28k%E5%87%8F4%29x%5E2%2Bkx+%28k%E5%B1%9E%E4%BA%8ER%29+%E5%AF%B9%E4%BB%BB%E6%84%8F%E5%AE%9E%E6%95%B0x%2Cf%28x%29%E5%B0%8F%E4%BA%8E%E7%AD%89%E4%BA%8E6x%2B2%E6%81%92%E6%88%90%E7%AB%8B%2C%E6%95%B0%E5%88%97%7Ban%7D%E6%BB%A1%E8%B6%B3an%2B1%3Df%28an%29+%281%29%E6%B1%82%E5%87%BD)
设二次函数f(x)=(k减4)x^2+kx (k属于R) 对任意实数x,f(x)小于等于6x+2恒成立,数列{an}满足an+1=f(an) ...设二次函数f(x)=(k减4)x^2+kx (k属于R) 对任意实数x,f(x)小于等于6x+2恒成立,数列{an}满足an+1=f(an) (1)求函
设二次函数f(x)=(k减4)x^2+kx (k属于R) 对任意实数x,f(x)小于等于6x+2恒成立,数列{an}满足an+1=f(an) ...
设二次函数f(x)=(k减4)x^2+kx (k属于R) 对任意实数x,f(x)小于等于6x+2恒成立,数列{an}满足an+1=f(an) (1)求函数f(x)的解析式和值域 (2)试写出一个区间(a,b)使得当a1属于(a,b)时,数列{an}在这个区间上是递增函数 急
设二次函数f(x)=(k减4)x^2+kx (k属于R) 对任意实数x,f(x)小于等于6x+2恒成立,数列{an}满足an+1=f(an) ...设二次函数f(x)=(k减4)x^2+kx (k属于R) 对任意实数x,f(x)小于等于6x+2恒成立,数列{an}满足an+1=f(an) (1)求函
解:f(x)=(k-4)x^2+kx<=6x+2
(k-4)x^2+(k-6)x-2<=0
k-4<0且:判别式=(k-6)^2+8(k-4)<=0得k=2
f(x)=-2(x-1/2)^2+1/2,值域{y|y<=1/2}
an+1=f(an)=-2an^2+2an
an+1-an=-2an^2+an>0
得0
(k-4)x^2+(k-6)x-2≤0 任何x恒成立,k-4<0,且(k-6)^2-4*(k-4)*(-2)≤0
化简为(k-2)^2≤0,故k=2 f(x)=-2x^2+2x=-2(x-1/2)^2+1/2 值域(无穷,1/2]
a(n+1)=-2an^2+2an a(n+1)-an=-2an^2+an>0 得0
k-4<0且:判别式=(k-6)^2+8(k-4)<=0得k=2
f(x)=-2(x-1/2)^2+1/2