化简(1 5x-1 2y) (1 4x 2 3y)-搜答案-搜搜做题作业网

sin(x+y)cos(x-y)+cos(x+y)sin(x-y)=sin(x+y+x-y)=sin2x再问：sin(x+y)cos(x-y)+cos(x+y)sin(x-y)为什么=sin(x+y+

3x=15,x=5,5+2y=19,y=7,y-x=2

(x平方-y平方)/(x+y)+(x平方-2xy+y平方)/(x-y)=(x+y)(x-y)/(x+y)+(x-y)^2/(x-y)=x-y+x-y=2(x-y)

{2/3x-2/(x+y)[(x+y)/3x-x-y]}/【(x-y)/x】的负二次方={2/3x-[2/(x+y)]*[(x+y)-3x(x+y)]/(3x)}*[x/(x-y)]^2={2/3x-

3x（2x+y)-2x(x-y)=6x^2+3xy-2x^2+2xy=4x^2+5xy=x(4x+5y)再答：采纳一下啊谢谢

这是一个问题还是分开的啊?再问：feikai再答：/代表几分之几,*代表乘号1.3x+8y=12①14x+5y=12②②-①=11x-3y=011x=3y11/3*x=y再代入①里计得x,再代入②再问

∵x-2y+z=（x-y）-（y-z）,x+y-2z=（y-z）-（z-x）,y+z-2x=（z-x）-（x-y）．设x-y=a,y-z=b,z-x=c,则原式=-ac/(a-b)(b-c)+(-ba

令a=x²+y²则a²-a=12a²-a-12=0(a-4)(a+3)=0a=4,a=-3平方数大于等于0所以a=-3不成立所以x²+y²=

x',y',z'是啥意思?没说是整数还是自然数,或者别的条件?(x-x')+(y+y')+z*z'=16这个式子也没有问题?条件不明确,本题有很多解.后面的两个限制条件没有用.x+y+z=14的自然数

解原式=(3x²+xy-9xy-3y²)-(4x²-12xy)+9y²)=(3x²-8xy-3y²)-(4x²-12xy+9y&#

3(X-Y)²-4(X-Y)+7(X-Y)-6(X-Y)²=(3-6)(X-Y)²+(-4+7)(X-Y)=-3(X-Y)²+3(X-Y)

（1）每一项系数为+1,-1交替；x和y的次数和为15（2）第n项为所以第10项为（3）15次16项式

(x+y)-(2x+y/2)-(3x+y/6)-(4x+y/12)-(5x+y/20)-……-(10x+y/90)=x-2x-3x-4x-..-10x+y*(1-1/2-1/6-1/12-..1/90

(x-3y)(x+y)-(x-2y)(x+2y)-(x-y)平方=x²-2xy-3y²-x²+4y²-x²+2xy-y²=(x²-

(x-y)^2+12(x-y)+36

(x-y)^2+12(x-y)+36=(x-y+6)²;很高兴为您解答,skyhunter002为您答疑解惑如果本题有什么不明白可以追问,再问：Guoc过程再答：(x-y)^2+12(x-y

{(x,y) |x|+|y|

区域是一个正方形

(2x-y)²-4(x-y)(x+y)=(4x²-4xy+y²)-4(x²-y²)=4x²-4xy+y²-4x²+4y&

x^3+x-30(分解因式)=(x^3-27)+(x-3)=(x-3)(x^2+3x+9)+(x-3)=(x-3)(x^2+3x+9+1)=(x-3)(x^2+3x+10);x^12-y^12;=(x

1 ,化简（x-y)(x+y)

（x-y)(x+y)=x²-y²（x+3)²=x²+6x+9(x-1)(x-2)=x²-3x+2√25=5

x>y?x:y

判断X的数值是否大于Y的数值如果是则为真等式去X的值反之取Y的值