enscape3.3.0怎么汉化

沈鸿侨3224已知数列an中,an>0,且Sn=1/2*(an+1/an),求a1,a2,a3,猜想通项公式,并加以证明. -
章红旭17078633664 ______ 令n=1,2,3,得到三个方程,联立求解得到a1=1,a2=(根号2)-1,a3=(根号3)-(根号2)猜测,an=(根号n)-(根号(n-1))...

沈鸿侨3224已知函数y=sinxcosx+sinx+cosx,求x∈【0,三分之派】时函数y的最值 -
章红旭17078633664 ______ 解:依题意 y=sinxcosx+sinx+cosx=1/2(2sinxcosx+1-1) +sinx+cosx=1/2((sinx+cosx)^2 -1)+sinx+cosx=1/2(sinx+cosx)^2+(sinx+cosx)-1/2 设t=sinx+cosx 则 y=1/2t^2+t-1/2=1/2(t^2+2t+1-1)-1/2=1/2(t+1)^2 -1 所以又因为t=sinx+cosx∈[-根号2,根号2] 所以 yMAX=1/2(根号2 + 1)^2 - 1 yMIN=-1/2

沈鸿侨3224已知等差数列an的首项a1及公差d都是整数,前n项和为Sn,若a1>1,a4>3,S3≤9,设bn=2n*an,则b1+b2 -
章红旭17078633664 ______ 解:S3=3a1+3d≤9a1+d≤3a2≤3a4>3,a4>a2,a4=a2+2d>a2 d>0,公差d>0,数列为递增数列.a1>1...