1、解方程:{x-2y=-1;3(x-2)=1-y {4x-3y=-2;x/4+y/6=3
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1、解方程:{x-2y=-1;3(x-2)=1-y {4x-3y=-2;x/4+y/6=3
2、先化简,再求值
(x-1)(x-2)-3x(x+3)-(x-1)^2,其中x=3
3、计算:(-1/2)^2/(-2)^3*(-2)^2
2、先化简,再求值
(x-1)(x-2)-3x(x+3)-(x-1)^2,其中x=3
3、计算:(-1/2)^2/(-2)^3*(-2)^2
x-2y=-1 ①
3(x-2)=1-y ②
由①,得x=2y-1 ③
将③代入②中,得
3(2y-3)=1-y
6y-9=1-y
7y=10
y=10/7
将y=10/7代入③中,得
x=20/7-1=13/7
4x-3y=-2 ①
x/4+y/6=3 ②
即3x+2y=36 ③
①×2,②×3,得
8x-6y=-4 ④
9x+6y=108 ⑤
④+⑤,得
17x=104
x=104/17
将x=104/17代入③中,得
y=150/17
(x-1)(x-2)-3x(x+3)-(x-1)^2
=x^2-3x+2-3x^2-9x-(x^2-2x+1)
=x^2-3x+2-3x^2-9x-x^2+2x-1
=-3x^2-10x+1
=-3×9-10×3+1
=-27-30+1
=-56
(-1/2)^2/(-2)^3×(-2)^2
=(1/4)/(-8)×4
=-1/32×4
=-1/8
3(x-2)=1-y ②
由①,得x=2y-1 ③
将③代入②中,得
3(2y-3)=1-y
6y-9=1-y
7y=10
y=10/7
将y=10/7代入③中,得
x=20/7-1=13/7
4x-3y=-2 ①
x/4+y/6=3 ②
即3x+2y=36 ③
①×2,②×3,得
8x-6y=-4 ④
9x+6y=108 ⑤
④+⑤,得
17x=104
x=104/17
将x=104/17代入③中,得
y=150/17
(x-1)(x-2)-3x(x+3)-(x-1)^2
=x^2-3x+2-3x^2-9x-(x^2-2x+1)
=x^2-3x+2-3x^2-9x-x^2+2x-1
=-3x^2-10x+1
=-3×9-10×3+1
=-27-30+1
=-56
(-1/2)^2/(-2)^3×(-2)^2
=(1/4)/(-8)×4
=-1/32×4
=-1/8
{3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1
化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1
解方程组:2(x-y)/3-x+y/4=-1 ,6(x+y)-4(2x-y)=16
解二元一次方程组{3(x+y)-4(x-y)=4,x+y/2+x-y/6=1
解方程组3(x+y)-4(x-y)=4和(x+y)/2+(x-y)/6=1
解二元一次方程组{3(x+y)-(x-y)=4,x+y/2+x-y/6=1
解二元一次方程组:3(x+y)-4(x-y)=4,x+y/2+x-y/6+1
解方程:3x+2y/4=2x+y/5=x-y+1/6要详细过程
已知x=1/3,y=-1/2,求代数式x-(x+y)+(x+2y)-(x+3y)+(x+4y)-(x+5y)+...-(
先化简再求值(x-y)(x+y)-(x-2y) 的完全平方+x(3x-5y)-(x-y)(x-2y),其中x=1/2 y
[(2x+y)^2+(y+2x)(y-2x)-2y(4x-y)]/4y,其中x=1/2,y=1/3
用代入法解方程2(x-y)/3-(x+y)/4=-1① 6(x+y)-4(2x-y)=16②