求代数式的值:
(1)6x+2x²-3x+x²+1,其中x=-5 ;
(2)4x²+3xy-x²-9,其中x=2,y= -3 ;
(3)3pq-4m/5-4pq,其中m=-5,p=-1/4,q=-3/2
有以下程序:void f(int *x,int *y){ int *t; t=x; x=y ;y=t; *x=*y;}main(){ int a[8]={1,2,3,4,5,6,7,8},i,*p,*q; p=a;q=&a[7]; while(p>q) { f(p,q);p++;q--} for(i=0;i<8;i++)printf("d,",a[i]);}程序运行后的输出结果是( )。A.8,2,3,4,5,6,7,1,B.5,6,7,8,1,2,3,4,C.1,2,3,4,5,6,7,8,D.8,7,6,5,4,3,2,1,
点击查看答案
下列程序的输出结果是( )。 void f(int*x,int*y) {int t; t=*x,*x=*y;*y=t; } main() {int a[8]={1,2,3,4,5,6,7,8},i,*p,*q; p=a;q=&a[7]; while(p<q) {f(p,q);p++;q--;} for(i=0;i<8;i+)printf("%d,",a[i]); }A.8,2,3,4,5,6,7,1B.5,6,7,8,1,2,3,4C.1,2,3,4,5,6,7,8D.8,7,6,5,4,3,2,1
化简下列各式: (1)3(xy-2z)+(-xy+3z); (2)-4(pq+pr)+(4pq+pr) ; (3)(2x-3y)-(5x-y) ; (4)-5(x-2y+1)-(1-3x+4y); (5)(2a²b-5ab)- 2(-ab-a²b) ; (6)1-3(x-½y²)+(-x+½y²)。
求下列各式的值:(1)3x²-(2x² + 5x-1)-(3x+1),其中 x =10 ; (2) (xy-3y/2-1/2)-(xy-3x/2+1),其中x=10/3,y=8/3;(3)4y²-(x²+y)+(x²-4y²),其中x=-28,y=18
化简下列各式:(1)5x4+3x2y-10-3x2+x-1; (2)p²+3pq+6-8p²+pq ;(3)(7y-3z)-(8y-5z); (4)-(a5-6b)-(-7+3b)(5)2(2a²+9b)+3(-5a²-4b);(6)-3(2x²-xy)+4(x²+xy-6).
求下列代数式的值:1)-3x²+5x-0.5x²+x-1,其中x=2;2)1/4×(-4x2+2x-8)-(x/2-1),其中1/2; 3)(5a²-3b²)+(a²+b²)-(5a²+3b²),其中a=-1,b=1;4)2(a²b+ab²)-2(a²b -1)-2ab²-2,其中a=-2,b=2.
解下列方程:(1)5x/12-x/4=1/3(2)2/3-8x=3-x/2(3)0.5x-0.7=6.5-1.3x(4)(3x-6)/6=2x/5-3(5)3(x-7)+5(x-4)=15(6)4x-3(20-x)=-4(7)(y-1)/2=2-[(y+2)/5](8)(1-2x)/3=2(3x+1)/7