设y=3x，则y′=（）。设y=3x，则y′=（）。
举一反三
- 设y=3x，则y’’=______．
- y= ln(3x)，则y'=( ) A: 1/(3x) B: 1/x
- 下列语句正确的是( ) A: If x<3*y And x>y Then y=3x B: If x<3*y And x>y Then y=x^3 C: If x<3*y : x>y Then y=x^3 D: If x<3*y And x>y Then y=x**3
- 如下C程序的输出是什么？#include [stdio.h]void Func1 (int x, int y);void Func2 (int *x, int *y); int main() { int x = 3; int y = 4;Func1 (x, y); printf ("x = %d, y = %d\n", x, y);Func2(&x, &y); printf ("x = %d, y = %d\n", x, y);} void Func1 (int x, int y) { x = x + y; y = x - y; x = x - y; printf ("x = %d, y = %d\n", x, y);} void Func2 (int *x, int *y) { *x = *x + *y; *y = *x - *y; *x = *x - *y;;} A: x = 3, y = 4x = 3, y = 4x = 3, y = 4 B: x = 4, y = 3x = 4, y = 3x = 4, y = 3 C: x = 3, y = 4x = 3, y = 4x = 4, y = 3 D: x = 4, y = 3x = 3, y = 4x = 4, y = 3
- 下面关系式，（ ）中的x和y成反比例． A: x3=y B: 3x=y C: 3x=y D: xy=3