关于x的方程((dfrac {1)(2))}^2x-5cdot (2)^-x+4=0有（）个实数解.A.1 B.2 C.3 D.0

lim _(xarrow 1)(dfrac (2)({x)^2-1}-dfrac (1)(x-1))= (-|||-A.1 B. -dfrac (1)(2) C

16.曲线 =(e)^dfrac (1{{x)^2}}arctan dfrac ({x)^2+x+1}((x-1)(x+2)) 的渐近线条数为 ()-|||-A

若方程组 ) 7(x)_(1)+8(x)_(2)+9(x)_(3)=0 -(x)_(2)+2(x)_(3)=0 2(x)_(2)+t(x)_(3)=0 .=

已知关于x的方程 ^2+(2k-3)x+(k)^2-3=0 有两个实数根x1,x2,且 _(1)+(x)_(2)=dfrac (1)({x)_(1)}+dfra

的解为 () .-|||-(A) x=2 =0, z=-2 ; (B) x=-2 =2 =0;-|||-(C) =0, =2, =-2; (D) x=1 =0,

解下列方程：（1）x2+10x+9=0；（2）x2-x-(7)/(4)=0；（3）3x2+6x-4=0；（4）4x2-6x-3=0；（5）x2+4x-9=2x-

一、单项选择题-|||-1.微分方程 ((y))^2=x 的阶数为 ()-|||-A.1 B.2 C.3 D.4

已知实数x满足(x)^2+dfrac (1)({x)^2}-3x-dfrac (3)(x)+2=0，求(x)^3+dfrac (1)({x)^3}的值.已知实数

+(x)_(n)=0 -(x)_(1)-(x)_(2)-... -(x)_(n)=0 . 的任意基础解系所含解向量的个-|||-数为 () .-|||-A 1

求下列齐次线性方程组的基础解系:(1) ) (x)_(1)-8(x)_(2)+10(x)_(3)+2(x)_(4)=0 2(x)_(1)+4(x)_(2)+5