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设n属于N+,一元二次方程x2-4x+n=0有整数根的充要条件是? 设n∈N+,一元二次方程x2-4x+n=0有整数根的充要条件是n= 设n属于正整数,一元二次方程x的平方-4x+n=0有整数根,则n=__________ 设n属于N,一元二次方程x2-4x+n=0有正数根的充要条件是n=?! The dictionary still _______ where I ______ it yesterday.You can find it easily.A.lies; laid B.lied; lay C.laid; laid D.lies; laywe should do to protect wildlife?A.What do you think B.What do you know C.Do you suggest what D.Do you think what 说明理由If he doesn’t go swimming this evening,__________.A.Nor shall I B.Neither do I C.So shall I D.I do neitherI don’t think he’s serious,_____?A.do I B.don’t I C.isn’t he D.is he 方程2y＋x＝7的正整数解是 1.方程x+2y=7有__个解,正整数解为____2.若x的a-b次方－2y的a+b-2的次方=3是二元一次方程,则2a-3b＝_____3.（x+y+3)的2次方+|2x-y-1|=0,则x/y的值是_____4.已知方程组{x+2y=n,4x-y=8 和{5x+3y=2,3x-4y=m有相同的解,那 若关于x的不等式(3x-b)/(x²+1) 已知实数xy满足等式3x²+2y²-6x=0,求w=x²+y²的取值范围 对任意x＞0,不等式x/x²+3x+1 ≤a恒成立,则实数a的取值范围?怎么算? ①关于x不等式(½)∧x²-2ax＜2∧3x a²对一切实数都成立,则a的取值范围是?②不等式log2(ax²+x+3)＞0的解集为R，则a的取值范围是！第一题的是+号3x+a² 急若不等式3x²+x+2k/x²+x+2＞2对一切实数x都成立,则K的取值范围是 方程x＋2y＝7在正整数范围内的解有几个 方程x+2y+z=5的正整数解为________（求方程过程） 1.The purpose of new techenologies is to make life easier,____it more difficult.a) not to make b)not make c)not making d)do not make2.The most important question about the computer is___it han done and will do to man.a)which b)that c)what d)when3.Pet 3道英语选择题,求详解麻烦详细解释一下～～谢谢!（ ）hearing the bad news, she immediately went home. A: at B:on C:while( ) he once went bankrupt, he thought of ending his life.A:whenever B:as 有3道英语选择题.1.If you plant watermelon seeds in the spring ,you( )fresh watermelon in the fall.A.eat B.would eat C.have eaten D.will be eating为什么不能选B啊?是不是后面不能用would那种的?2.For many years,people( )electric c 如图两块斜边长相等的直角三角板拼在一起,若向量AD=X向量AB+Y向量AC,则X=?Y=?（给我解释一哈哈） 方程x^4-1-a=0无解,求a的取值范围 若方程a^x=x+a有一个解,则a的取值范围是 A.a>1 B.0 若关于x的方程（2x+a）/( x-1)- (x+2)/( x-2) =1 有解,求a的取值范围.若改为无解,如何求a的取值范围.（2x+a）/( x-1)- (x+2)/( x-2) =1 是一个分式方程. 若方程 √(x^2-1)=x+m无解,则实数m的取值范围是：__________RT求过程或思路答案：m 3x^2-7x-1=0的根x1= ,x2= ; 把二次三项式3x^2-7x-1分解因式,得 . 分解因式3x^4-7X^2+2用韦达定理 3x'3-7x'2+4分解因式 请问对于一个函数在确定自变量取值范围时不仅要考虑有意义而且还要注意问题的什么 函数自变量的取值范围就是使...有意义的那些...的取值 函数自变量的取值范围,主要从两个方面考虑:一是自变量的取值要使___有意义,二是自变量的取值也要使__有意 已知a,b是两个非零向量,夹角为α,当a+tb(t∈R）的模取最小值时（1）求t的值 （2）求b与a+tb的夹角 以上a,b都是向量哈. 关于x的方程3x-（2a-3）=4x+（3a+6）的解大于十二,求a的取值范围,不采纳! 1 he left ___ without saying anythingA in the hurry B in a hurry C with hurry D in hurry 2 I'll go with ___A the smith brothers' Bthe smith's brothers Cthe smiths brothers