呈味核苷酸二钠的作用

已知抛物线C：x²=4y的焦点为F,直线L:y=kx+2与C交于A、B两点.（1）当K=1/2时,求cos ∠AFB的值.(2)过A,B两点分别作抛物线C的切线,两条切线的交点为M,设线段AB的中点为N,试探究是否存在λ∈R使得向 （急!）高二数学圆锥曲线与方程1.过双曲线的一个焦点F2作垂直与实轴的弦PQ.F1为另一个焦点,若角PF1Q=90度,则双曲线的离心率＝?2.直线y=1-x交椭圆mx^2+ny^2=1于M.N两点,弦MN的中点为p,若OP的斜率等 在三角形ABC中,AB=c,AC=b,BC=a,且a>b>c,a,b,c成等差数列,若顶点A、C是定点,且|AC|=2,求满足上述条件的点B的轨迹方程. 已知函数y=-x^2+2x的定义域为[-2,2],求它的最小值和减区间 定义域为［a,b］的减函数f(x)的最大值为 最小值为 y1=X+3 y2=2-x当x取几时y1=y2?当x取几是y1比y2大5? 2.He is the first black president in American history.1).在②处的划线句子中找出两个可以连读的词：______________________2) 在②处的划线句子中哪个词的最后一个音可以失去爆破?____________求英语高手,急 完成句子 Obama is America 's first black preident______[他的母亲是一位教师】 my dream home作文1.What is your dream home like?2.How many rooms are there in your dream home and what are they?3.What are in the rooms ?4.Is there any other information about your dream home? 英文小作文 my dream home 9分之8乘9分之8除9分之8乘9分之8急简便计算 (12/7加9/2加8/3)乘72综合算式,完整. 初三表格化学计算题.质量分数什么的,需要详细过程为了测定某铜锌合金（即铜锌混合物）中锌的质量分数,某同学利用该合金与稀硫酸反应,进行了三次实验.所得相关数据记录如下（实验中 抽象函数单调性已知定义在（0,正无穷）上的函数f(x)对任意x,y属于（0,正无穷）恒有f(xy)=f(x)+f(y) 且当0 Abraham Lincoln is generally considered_____the greatest president of America. A to be B as C 不填 D all of the above 答案为D 请帮忙分析一下这个句子.我不是很懂. 书上说consider 作‘认为’的时候后面可以跟to be的结 抽象函数单调性证明已知f（x）是R上的偶函数,且在（0,+∞)上单调递增,并且f（x）＜0对一切x∈R成立,试判断-1/f（x）在（-∞,0）上的单调性,并证明你的结论.不仅要判断还要证明 主要是证明 [请教一道高一英语题]Abraham Lincoln is generally considered_____the greatest president of America.Abraham Lincoln is generally considered_____the greatest president of America.A to be B as C 不填 D all of the above请帮忙分析一下这 Abraham Lincoln ,President of the United States ,was not vrey handsome and h In 1861 Abraham Lincoln became the United States’ sixteenth president. Five weeks ______1______ the Civil War began It was a _____2______ about slavery . Lincoln had two main ____3____: he wanted to free the slaves and he wanted divided into two n 己知a为锐角,sin（a加15度）=2分之根号3,计算根号8-4cosa+tana+（3分之一）的-1次方的值 What are the advantages and disadvantages of plastic surgery?谁能帮我写一篇整容手术的优缺点的英语作文,最好是以英语口语形式写的.写个5句就行 what are the advantages and disadvantages of Intrernetabout comversation what are the advantages and disadvantages of obortion?用英文表达一下.越快越好啦.我的意思是,用英语表达一下流产得利与弊啊。也就是写一篇小文章得意思啦。 若2x-3的绝对值与y+3的绝对值互为相反数,求x+y的相反数? 抽象函数的单调性已知任意m.n都是f（m+n）=f(m)+f（n)-1,当x>0时,f(x)>1求：若f（3）=4,解不等式f(a的平方+a-5） 抽象函数单调性.定义在R上的函数y=f（x）,对任意的a、b属于R,满足f（a+b）=f（a）*f（b）,当x大于0时,有f（x）大于1,其实f（1）=2,f（0）=1 . 求证：f（x）是单调增函数.证：令a=x,b=-x,则f（0）=f（ 已知A+B=π/6,（根号3）(tanAtanB+a)+2tanA+3tanB=0,则tana=?打错了，是求tanA的值！2.已知sinα+sinβ=根号2/2，则cosα+cosβ的取值范围是___________________ 已知-π/2 We had better_____(stay)at home. You'd better stay at home.The r___ is heavy outside. 英语填空题：It's raining ________（heavy）outside.You'd better stay at home now. family tree的中文翻译