a) 2xy-6x+y = 8
b) xy+3x-2y= 6
Tìm x,y thuộc Z:
a,xy+2y-y=9
b,2xy-6x+y=13
c,xy-3x-3y=6
GIÚP MÌNH VỚI
Các bài đều giống nhau:
a/ \(xy+2x-y=9\Leftrightarrow x\left(y+2\right)-\left(y+2\right)=7\)
\(\Leftrightarrow\left(x-1\right)\left(y+2\right)=7\)
Đến đây thì chia trường hợp thôi:
\(\left\{{}\begin{matrix}x-1=7\\y+2=1\end{matrix}\right.\) ;\(\left\{{}\begin{matrix}x-1=1\\y+2=7\end{matrix}\right.\); \(\left\{{}\begin{matrix}x-1=-1\\y+2=-7\end{matrix}\right.\);\(\left\{{}\begin{matrix}x-1=-7\\y+2=-1\end{matrix}\right.\)
Bạn tử giải ra tìm x, y, nếu nghiệm nào ko nguyên thì loại, nhưng câu này nguyên hết
b/ \(2xy-6x+y=13\Leftrightarrow2x\left(y-3\right)+y-3=10\)
\(\Leftrightarrow\left(2x+1\right)\left(y-3\right)=10\)
Làm y hệt câu trên, lưu ý \(2x+1\) luôn lẻ nên nó chỉ có thể là các ước lẻ của 10 như \(\pm1;\pm5\)
c/ \(xy-3x-3y=6\Leftrightarrow x\left(y-3\right)-3y+9=15\)
\(\Leftrightarrow x\left(y-3\right)-3\left(y-3\right)=15\Leftrightarrow\left(x-3\right)\left(y-3\right)=15\)
a) Xem lại đề ?
b) 2xy - 6x +y = 13
=> 4xy - 12x + 2y =26
=> 4x( y - 3 ) + 2(y-3) = 26 - 6 = 20
=> (4x+2) (y-3 ) = 20
Lập bảng để tìm x,y
c) xy - 3x - 3y = 6
=> x( y -3 ) - 3(y-3 )=12
=> (x-3)(y-3) =12
phân tích đa tử
a,xy+3x-7y-21
b,2xy-15-6x+5y
2x^2y+2x^2y-x-y
d,7x^3y-3xyz-21x^2+9z
e, 4x^2 -2x -y^2-y
f, 9x^2-25y^2 -6x+10y
a
\(xy+3x-7y-21\\ =\left(xy+3x\right)-\left(7y+21\right)\\ =x\left(y+3\right)-7\left(y+3\right)\\ =\left(y+3\right)\left(x-7\right)\)
b
\(2xy-15-6x+5y\\ =\left(2xy-6x\right)-\left(15-5y\right)\\ =2x\left(y-3\right)-5\left(3-y\right)\\ =2x\left(y-3\right)+5\left(y-3\right)\\ =\left(y-3\right)\left(2x+5\right)\)
c Đề phải là \(\left(2x^2y+2xy^2-x-y\right)\) mới phân tích được: )
\(=2xy\left(x+y\right)-\left(x+y\right)\\ =\left(x+y\right)\left(2xy-1\right)\)
d
\(7x^3y-3xyz-21x^2+9z\\ =\left(7x^3y-21x^2\right)-\left(3xyz-9z\right)\\ =7x^2\left(xy-3\right)-3z\left(xy-3\right)\\ =\left(xy-3\right)\left(7x^2-3z\right)\)
e
\(4x^2-2x-y^2-y\\ =\left(2x\right)^2-y^2-\left(2x+y\right)\\ =\left(2x-y\right)\left(2x+y\right)-\left(2x+y\right)\\ =\left(2x+y\right)\left(2x-y-1\right)\)
f
\(9x^2-25y^2-6x+10y\\ =\left(3x\right)^2-\left(5y\right)^2-\left(6x-10y\right)\\ =\left(3x-5y\right)\left(3x+5y\right)-2\left(3x-5y\right)\\ =\left(3x-5y\right)\left(3x+5y-2\right)\)
a: =x(y+3)-7(y+3)
=(y+3)(x-7)
b: \(=2xy-6x+5y-15\)
=2x(y-3)+5(y-3)
=(y-3)(2x+5)
c: \(=2xy\left(x+y\right)-\left(x+y\right)=\left(x+y\right)\left(2xy-1\right)\)
d: \(=xy\left(7x^2-3z\right)-3\left(7x^2-3z\right)\)
=(7x^2-3z)(xy-3)
e: =4x^2-y^2-2x-y
=(2x-y)(2x+y)-(2x+y)
=(2x+y)(2x-y-1)
f: =(3x-5y)(3x+5y)-2(3x-5y)
=(3x-5y)(3x+5y-2)
Tìm số nguyên x biết
a,3x+3y-2xy=7
b,xy+2x+y+11=0
c,xy+x-y=4
d,2x.(3y-2)+(3y-2)=12
e,3x+4y-xy=15
f,xy+3x-2y=11
g,xy+12=x+y
h,xy-2x-y=-6
i,xy+4x=25+5y
ii,2xy-6y+x=9
iii,xy-x+2y=3
k,2.x^2.y-x^2-2y-2=0
l,x^2.y-x+xy=6
a) ( -3x^2y - 2xy^2 +6) + (-x2y + 5xy^2 -1) b) (1,6x^3 -3,8x^2y) + (-2,2x^2y - 1,6x^3 + 0,5xy^2) c) (6,7xy^2 - 2,7xy + 5y^2) - (1,3xy - 3,3xy^2 + 5y^2) d) ( 3x^2 - 2xy + y^2) + (x^2 -xy + 2y^2) - ( 4x^2 - y^2) e) ( x^2 + y^2 - 2xy) - ( x^2 + y^2 + 2xy) + ( 4xy -1)
\(a)\left(-3x^2y-2xy^2+6\right)+\left(-x^2y+5xy^2-1\right)\)
\(=-3x^2y-2xy^2+6+-x^2y+5xy^2-1\)
\(=\left(-3x^2y-x^2y\right)+\left(-2xy^2+5xy^2\right)+\left(6-1\right)\)
\(=-4x^2y+3xy^2+5\)
\(b)\left(1,6x^3-3,8x^2y\right)+\left(-2,2x^2y-1,6x^3+0,5xy^2\right)\)
\(=1,6x^3-3,8x^2y+-2,2x^2y-1,6x^3+0,5xy^2\)
\(=\left(1,6x^3-1,6x^3\right)+\left(-3,8x^2y+-2,2x^2y\right)+0,5xy^2\)
\(=-6x^2y+0,5xy^2\)
\(c)\left(6,7xy^2-2,7xy+5y^2\right)-\left(1,3xy-3,3xy^2+5y^2\right)\)
\(=6,7xy^2-2,7xy+5y^2-1,3xy+3,3xy^2-5y^2\)
\(=\left(6,7xy^2+3,3xy^2\right)+\left(-2,7xy-1,3xy\right)+\left(5y^2-5y^2\right)\)
\(=10xy^2+-4xy\)
\(=10xy^2-4xy\)
\(d)\left(3x^2-2xy+y^2\right)+\left(x^2-xy+2y^2\right)-\left(4x^2-y^2\right)\)
\(=3x^2-2xy+y^2+x^2-xy+2y^2-4x^2+y^2\)
\(=\left(3x^2+x^2-4x^2\right)+\left(-2xy-xy\right)+\left(y^2+2y^2+y^2\right)\)
\(=-3xy+4y^2\)
\(e)\left(x^2+y^2-2xy\right)-\left(x^2+y^2+2xy\right)+\left(4xy-1\right)\)
\(=x^2+y^2-2xy-x^2-y^2-2xy+4xy-1\)
\(=\left(x^2-x^2\right)+\left(y^2-y^2\right)+\left(-2xy-2xy+4xy\right)-1\)
\(=-1\)
2) tính a)3x(3x+6). b)-1/2xy(4x^2+6x). c)-2x^2y^3(1/2xy+4y^2). d)-6x^2(1/3xy^2-1/2y)
\(a,3x\left(3x+6\right)=9x^2+18x\)
\(b,-\dfrac{1}{2}xy\left(4x^2+6x\right)\)
\(=-2x^3y-3x^2y\)
\(c,-2x^2y^3\left(\dfrac{1}{2}xy+4y^2\right)\)
\(=-x^3y^4-8x^2y^5\)
\(d,-6x^2\left(\dfrac{1}{3}xy^2-\dfrac{1}{2}y\right)\)
\(=-2x^3y^2+3x^2y\)
#\(Urushi\)
a) 3x(3x+6) = 9x^2 + 18x b) -1/2xy(4x^2+6x) = -2x^3y - 3xy c) -2x^2y^3(1/2xy+4y^2 ) = -x^2y^2 - 8x^2y^5 d) -6x^2(1/3xy^2-1/2y) = -2xy + 3x^2y
Vậy kết quả của các biểu thức là: a) 9x^2 + 18x b) -2x^3y - 3xy c) -x^2y^2 - 8x^2y^5 d) -2xy + 3x^2y
bài 1:tìm x;y thuộc Z
1)6.(x-2)-y.(2-x)=10
2)3x-2xy+3y=6
3)6x-xy+2y=5
Giai hộ mình nhé mình cần lời giải chi tiết đúng thì mình sẽ tick cho nhé
BT11: Tìm hiệu A-B biết
\(a,-x^2y+A+2xy^2-B=3x^2y-4xy^2\)
\(b,5xy^2-A-6yx^2+B=-7xy^2+8x^2y\)
\(c,3x^2y^3-A-5x^3y^2+B=8x^2y^3-4x^3y\)
\(d,-6x^2y^3+A-3x^3y^2-B=2x^2y^3-7x^3y\)
\(e,A-\dfrac{3}{8}xy^2-B+\dfrac{5}{6}x^2y=\dfrac{3}{4}x^2y-\dfrac{5}{8}xy^2\)
\(f,5xy^3-A-\dfrac{5}{8}yx^3+B=\dfrac{21}{4}xy^3-\dfrac{7}{6}x^3y\)
a: =>A-B=3x^2y-4xy^2+x^2y-2xy^2=4x^2y-6xy^2
b: =>B-A=-7xy^2+8x^2y-5xy^2+6x^2y=-12xy^2+14x^2y
=>A-B=12xy^2-14x^2y
c: =>B-A=8x^2y^3-4x^3y-3x^2y^3+5x^3y^2=5x^2y^3+x^3y^2
=>A-B=-5x^2y^3-x^3y^2
d: =>A-B=2x^2y^3-7x^3y+6x^2y^3+3x^3y^2=8x^2y^3-7x^3y+3x^3y^2
Rút gọn:
a) \(\frac{x^2+y^2-1+2xy}{x^2-y^2+1+2x}\)
b) \(\frac{3x^3-6x^2y+xy^2-2y^3}{9x^5-18x^4y-xy^4+2y^5}\)
a)\(\frac{x^2+y^2-1+2xy}{x^2-y^2+1+2x}\)
\(\Leftrightarrow\frac{\left(x+y\right)^2-1}{\left(x+1\right)^2-y^2}\)
\(\Leftrightarrow\frac{\left(x+y+1\right)\left(x+y-1\right)}{\left(x+1-y\right)\left(x+1+y\right)}\)
\(\Leftrightarrow\frac{x+y-1}{x-y+1}\)
b)\(\frac{3x^3-6x^2y+xy^2-2y^3}{9x^5-18x^4y-xy^4+2y^5}\)
\(\Leftrightarrow\frac{3x^2\left(x-2y\right)+y^2\left(x-2y\right)}{9x^4\left(x-2y\right)-y^4\left(x-2y\right)}\)
\(\Leftrightarrow\frac{\left(3x^2+y^2\right)\left(x-2y\right)}{\left(9x^4-y^4\right)\left(x-2y\right)}\)
\(\Leftrightarrow\frac{3x^2+y^2}{\left(3x^2-y^2\right)\left(3x^2+y^2\right)}\)
\(\Leftrightarrow\frac{1}{3x^2-y^2}\)
6) Tính a)2xy(3x+1) b)-6x^2y(4x-5) c)-3x^2(4x^2y-6xy) d1/2xy^2(2x+3) e)8x^2y^2(1/4xy-1/2x^2) f)5x(x^2+3x+1) g)-1/2x^2y(2xy+6)
Để tính các biểu thức trên, ta sẽ áp dụng quy tắc nhân đa thức.
a) 2xy(3x+1) = 6x^2y + 2xy
b) -6x^2y(4x-5) = -24x^3y + 30x^2y
c) -3x^2(4x^2y-6xy) = -12x^4y + 18x^3y
d) 1/2xy^2(2x+3) = xy^2 + 3/2xy^2
e) 8x^2y^2(1/4xy-1/2x^2) = 2xy - 4x^2y^2
f) 5x(x^2+3x+1) = 5x^3 + 15x^2 + 5x
g) -1/2x^2y(2xy+6) = -x^3y - 3x^2y