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4x 3y 15 3x 2y 7

1. 17x-3y=74 (1) 8x+9y=73 (2) (1)*3+(2) 59x=295 x=5 y=(17x-74)/3=11/3 2. 4x+3y=3 (1) 3x-2y=15 (2) (1)*2+(2)*3 17x=51 x=3 y=(3x-15)/2=-3 3. 2x-3y=7 (1) 5x-3y=1 (2) (2)-(1) 3x=-6 x=-2 y=(5x-1)/3=-11/3 4. x-y=2 (1) 3x-4y=3 (2) (1)...

3x+2y-k=1,(1) 4x+3y-k=-1 (2) (1)×4 - (2)×3 : -y= k+7 y=-k-7 代入到(1): 3x-3k = 15 x= k+5 x-y>0 所以:(k+5) - (-k-7)>0 2k+12>0 2k>-12 k>-6

(1)原式=-28x5y2+12x5y4-32x9y4;(2)原式=4y2-12xy+9y2-x2+4y=23x2-12xy+13y2;(3)原式=x10÷x6=x4;(4)原式=1-8(a+2)(a-2)×[a2+4-4a4a×2aa-2]=1-8(a+2)(a-2)×a-22=a-2a+2.

4x+3y=15 2x-y=17 两式相减:2x+4y=-2 即:x+2y=-1 因此(x+2y)^2006=1

=2(4x²-3y²)+2(3x²+2y²) =52

3x+2y=k+1,两边同时乘以7: 21x+14y=7k+7 4x+3y=k-1,两边同时乘以5: 20x+15y=5k-5 上面两式相减: x-y=2k+12 由x-y>0,得:2k+12>0 得:k>-6

解方程组,得: X=K+5 Y=-K-7 若要X大于Y,则K+5大于-K-7,得K大于-6

3x+2y=m+1........................① 4x+3y=m-1........................② ①式乘以 3 得: 9x+6y=3m+3................③ ②式乘以 2 得: 8x+6y=2m-2................④ ③式减去④式 得: x=m+5 将 x 代入①式 得: 3(m+5)+2y=m+1 3m+15+2y=m+1 2y=-2m-1...

解: 3x+2y=k+1① 4x+3y=k-1② ①×3-②×2得 9x+6y-8x-6y=3k+3-2k+2 x=k+5 y=-k-7 因为 x>y 得 k+5>-k-7 解得 k>-6 k取负整数为:-5、-4、-3、-2、-1 愿对你有所帮助!

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