Tìm đa thức M, N biết:
a. \(M+\left(5x^2-2xy\right)=6x^2+9xy-y^2\)
b. \(\left(3xy-4y^2\right)-N=x^2-7xy+8y^2\)
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a/
\(M+5x^2-2xy-6x^2-9xy+y^2=0\)
\(M-x^2-11xy+y^2=0\)
\(M-x^2+y^2-11xy=0\)
\(M=x^2-y^2+11xy\)
Vậy:..
Câu b tương tự
a: \(M=6x^2+9xy-y^2-5x^2+2xy=x^2+11xy-y^2\)
b: \(N=3xy-4y^2-x^2+7xy-8y^2=-x^2+10xy-12y^2\)
a) Có:
\(M+\left(5x^2-2xy\right)=6x^2+9xy-y^2\)
\(\Rightarrow M=6x^2+9xy-y^2-\left(5x^2-2xy\right)\)
\(M=6x^2+9xy-y^2-5x^2+2xy\)
\(M=\left(6x^2-5x^2\right)+\left(9xy+2xy\right)-y^2\)
\(\Rightarrow M=x^2+11xy-y^2\)
b) Có:
\(\left(3xy-4y^2\right)-N=x^2-7xy+8y^2\)
\(\Rightarrow N=3xy-4y^2-\left(x^2-7xy+8y^2\right)\)
\(N=3xy-4y^2-x^2+7xy-8y^2\)
\(N=\left(3xy+7xy\right)+\left(-4y^2-8y^2\right)-x^2\)
\(\Rightarrow N=10xy+\left(-12y^2\right)-x^2\)
Hay \(N=10xy-12y^2-x^2\)
Chúc bạn học tốt!
a, M= 6x^2+9xy -y^2-5x^2+2xy
M= x^2 + 11xy - y^2
b, N = 3xy - 4y^2 - x^2 + 7xy - 8y^2
N= 10xy - 12y^2- x^2
a, M= 6x^2+9xy -y^2-5x^2+2xy
M= x^2 + 11xy - y^2
b, N = 3xy - 4y^2 - x^2 + 7xy - 8y^2
N= 10xy - 12y^2- x^2
chúc bn hok tốt @_@
Bài 3:
a: \(\Leftrightarrow M=6x^2+9xy-y^2-5x^2+2xy=x^2+11xy-y^2\)
b: \(\Leftrightarrow N=3xy-4y^2-x^2+7xy-8y^2=-x^2+10xy-12y^2\)
Bài 2:
\(A+B=4x^4-5xy+5y^2+3x^2+2xy-y=4x^4+3x^2-3xy+5y^2-y\)
\(A-B=4x^4-5xy+5y^2-3x^2-2xy+y=4x^4-3x^2+5y^2-7xy+y\)
\(B-A=-\left(A-B\right)=-4x^4+3x^2-5y^2+7xy-y\)
a, (6x2+9xy-y2) - ( 5x2-2xy)=M
=> M= (6x2+9xy-y2) - ( 5x2-2xy)
=> M= 6x2+9xy-y2 - 5x2+2xy
=> M=(6x2- 5x2)+(9xy+2xy)-y2
=>M= 1x2 + 11xy - y2
Vậy M= 1x2 + 11xy - y2
b, N= (3xy-4y2) - (x2-7xy+8y2)
=> N= 3xy-4y2 - x2+7xy-8y2
=> N= (3xy+7xy)-(4y2+8y2)-x2
=> N= 10xy - 12y2 -x2
Vậy N= 10xy - 12y2 -x2
Chúc bạn học tốt nha!!!
a, M+(5x2-2xy)=6x2+9xy-y2
\(\Rightarrow\)M= (6x2+9xy-y2)-(5x2-2xy)
= 6x2+9xy-y2-5x2+2xy
= (6x2-5x2)+(9xy+2xy)-y2
= x2+11xy-y2
Vậy đa thức M= x2+11xy-y2
b, (3xy-4y2)-N=x2-7xy+8y2
\(\Rightarrow\)N= (3xy-4y2)-(x2-7xy+8y2)
= 3xy-4y2-x2+7xy-8y2
= (3xy+7xy)+(-4y2-8y2)-x2
= 10xy-12y2-x2
Vậy đa thức N=10xy-12y2-x2
a, \(A=-x^2+4xy^2-2xz+3y^2\)
b, \(B=6x^2+9xy-y^2-5x^2+2xy=x^2+11xy-y^2\)
c, \(A=3xy-4y^2-x^2+7xy-8y^2=-x^2+10xy-12y^2\)
\(M=6x^2+9xy-y^2-5x^2+2xy\)
\(M=x^2+11xy-y^2\)
\(N=3xy-4y^2-x^2+7xy-8y^2\)
\(N=-x^2+10xy-12y^2\)
a. \(M+\left(5x^2-2xy\right)=6x^2+9xy-y^2\)
\(\Rightarrow M=6x^2+9xy-y^2-5x^2+2xy\)
b. \(\left(3xy-4y^2\right)-N=x^2-7xy+8y^2\)
\(\Rightarrow N=3xy-4y^2-x^2+7xy-8y^2\)