1 2 兀 3)x (1 3 兀 2)y-4-兀=0求x-y的值.-搜答案-搜搜考试网

此题是错的!这是因为cos²(X+Y)+sin²(X+Y)=5121/4225≠1,这与cos²(X+Y)+sin²(X+Y)=1矛盾.

写清楚点点比如说前面是X/X还是X/(X-Y)打上括号分段这样才能清楚的做

(x-3y)(y+2x)-(4y-3x)(3x+4y)=2x^2-3y^2-5xy+9x^2-16y^2=11x^2-5xy-19y^2

(2x+y)(2x-3y)+x(2y+y)=(2y+y)(2x-3y+x)=(2y+y)(3x-3y)=3(2y+y)(x-y)2a(x-y)-4b(x-y)=2(x-y)(a-2b)

2x-y/x+3y=2得x+3y/2x-y=1/24x-2y/x+3y减4x+12y除以2x-y=2(2x-y)/x+3y-4(x+3y)/2x-y=2乘以2-4乖以1/2=4-2=2

(-4x^2)/(-2x)+12x^3y^2/(-4x^2y)-24x^4y^3/(-4x^3y^2)=2x-3xy+6xy=2x+3xy=x(2+3y)=(-2)*(2+3/4)=-2*11/4=-

（x+2)(x+3)=x²+5x+6(x-4)(x+1)=x²-3x-4(y+4)(y-2)=y²+2y-8(y-5)(y-3)=y²-8y+15x²

原式=(9x^2-3xy+1/4y^2+3xy-1/4y^2)÷(4x^2+4xy+u^2-4xy-y^2)=9x^2÷4x^2=9/4

答案是2.4x-2y/x+3y=(2x-y/x+3y)乘以2=4,4x+12y/2x-y=(x+3y/2x-y)乘以4=1/2x4=2,所以代数式等于4-2=2.

6x^4y^3+12x^3y^4-24x^2y^5提取6x^2y^3=6x^2y^3(x^2+2xy-4y^3)

(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

16(x+y)^8/9(x-y)^8=16/9*[(x+y)/(x-y)]^8哪个好理解用哪个.再问：有过程没。。。再答：这个过程其实没什么好研究的。。。[3(x-y)^2(x+y)^-2/4(x+y

原式=(9x^2-3xy+1/4y^2+3xy-1/4y^2)÷(4x^2+4xy+u^2-4xy-y^2)=9x^2÷4x^2=9/4

∵π/2

设a=x+y,b=x-y原方程组为：a/2+b/3=6,即3a+2b=36,即：12a+8b=1444a-5b=12,即：12a-15b=36相减得：23b=108,得：b=108/23,再得：a=1

(2x-y)(2x+y)-2(3x-4y)(4y+3x)=4x²-y²-2(9x²-16y²)=4x²-y²-18x²+32y&s

12-x+2y=12-(x-2y)=12-5=73x-4y=2x+yx=5yx:y=5:1

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

(x+3y-4)(2x-y)

原式等于2x^2-xy+6xy-3y^2-8x+4y=2x^2+5xy-3y^2-8x+4y