已知\( y = {x^2} + 4x \)，则\( dy \)为（ ）. A: \( (2x + 4)dx \) B: \( 2xdx \) C: \( ({x^2} + 4)dx \) D: \( ({x^2} + 4x)dx \)

(4)()#include()extern()serial_initial()();()main()(){()int()a,b();()unsigned()int()x,y();()serial_initial()();()a=b=0xaa55();x=y=0xaa55;()printf("\n()a=%4x()b=%4x()x=%4x()y=%4x",a,b,x,y)();()a=a<<1();b=b>>1;()x=x<<1();y=y>>1;()printf("\n()a=%4x()b=%4x()x=%4x()y=%4x",a,b,x,y)();()printf("\n")();()printf("\n")();()printf("That()is()all.\n")();()while(1)();()}()______________________________________________________________________________________________________________________________

如下C程序的输出是什么？#include &#91;stdio.h&#93;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

y﹦|4x-x²|去绝对值后是y=-x²+4,还是y=x²-4x?

已知函数f(x)是定义在(-∞,+∞)上的奇函数,当x∈[0,+∞)时,f(x)=x()2()-4x,则当x∈(-∞,0)时,f(x)=()(5.0分)A.()x()2()+4x()B.()x()2()-4x()C.()-x()2()+4x()D.()-x()2()-4x

将函数\(f(x)=\sin^4 x\)展开成Fourier级数为 ____ . A: \(f(x) = \frac{3}{8}-\frac{1}{2}\cos 2x +\frac{1}{8}cos 4x\) B: \(f(x) = \frac{1}{4}-\frac{1}{2}\cos x +\frac{3}{8}cos 4x\) C: \(f(x) = \frac{1}{4}-\frac{1}{2}\sin 2x -\frac{3}{8}cos 4x\) D: \(f(x) = \frac{3}{8}-\frac{1}{2}\sin x -\frac{1}{8}cos 4x\)

令A=(P 1 P 2 P 3 P 4 P 5 P 6),(P 2 P 3 P 4 P 5)是一个基,则( )一定是基变量。 A: X IX 2X 3X 4 B: X 2X 3X 4X 6 C: X 3X 4X 5X 6 D: X 2X 3X 4X 5

（x^4x）(x^21)

\( y = 2 - x \) ，\( {y^2} = 4x + 4 \) 所围图形面积为64。

已知x²+xy=5,xy+y²=-4,求（1）x²-y²的值；（2）4x²+xy-3y²的值