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a, \(M-\left(3xy-4y^2-2xy\right)=\left(x^2-7xy+8y^2\right)\)
\(\Rightarrow M=\left(x^2-7xy+8y^2\right)+\left(3xy-4y^2-2xy\right)\)
\(\Rightarrow M=x^2-7xy+8y^2+3xy-4y^2-2xy\)
\(\Rightarrow M=x^2+\left[3xy-7xy-2xy\right]+\left[8y^2-4y^2\right]\)
\(\Rightarrow M=x^2-6xy+4y^2\)
b, \(N+\left(x^3-xyz+3x^2y\right)=2x^3+3xy-xy^2\)
\(\Rightarrow N=\left(2x^3+3xy-xy^2\right)-\left(x^3-xyz+3x^2y\right)\)
\(\Rightarrow N=2x^3+3xy-xy^2-x^3+xyz-3x^2y\)
\(\Rightarrow N=\left[2x^3-x^3\right]+3xy-xy^2+xyz-3x^2y\)
\(\Rightarrow N=x^3+3xy-xy^2+xyz-3x^2y\)
Tích mình nha!!!
a: \(M=6x^2+9xy-y^2-5x^2+2xy=x^2+7xy-y^2\)
b: \(M=-7xyz-15x^2yz^2+2xy^3\)
c: \(M=25u^2v-13uv^2+u^3-11u^2v+2u^3=14u^2v-13uv^2+3u^3\)
d: \(M=x^2-7xy+8y^2+4xy-3y^2=x^2-3xy+5y^2\)
a)M= 3,5x2y-2xy+1,5x2y+2xy+3xy2
M= (3,5x2y+1,5x2y)+(-2xy+2xy)+3xy2
M=5x2y+3xy2
N= 2x2y+3,2xy+xy2-4xy2-1,2xy
N= (xy2-4xy2)+(3,2xy-1,2xy)+2x2y
N=-3xy2+2xy+2x2y
b) ta có M=5x2y+3xy2 (đã thu gọn)
N=-3xy2+2x2y+2xy (đã thu gọn)
=> M-N=(5x2y+3xy2)+(-3xy2+2x2y+2xy)
M-N=5x2y+3xy2-3xy2+2x2y+2xy
M-N=(5x2y+2x2y)+(3xy2-3xy2)+2xy
M-N=7x2y+2xy
Hy vọng là đúng ạ!!!
Ta có M = x3 + x2y - 2x2 - xy - y2 +3y + x + 2017
= x2(x + y - 2) - y(x + y - 2) + x + y - 2 + 2019
thay x + y - 2 = 0 vào M ta có : M = x2.0 - y.0 + 0 + 2019
= 2019
\(M=x^3+x^2y-2x^2-xy-y^2+3y+x+2017\)
\(=\left(x^3+x^2y-2x^2\right)-\left(xy+y^2-2y\right)+\left(y+x-2\right)+2019\)
\(=x^2\left(x+y-2\right)-y\left(x+y-2\right)+\left(x+y-2\right)+2019\)
\(=\left(x+y-2\right)\left(x^2-y+1\right)+2019\)
Thay \(x+y-2=0\)vào đa thức ta được:
\(M=0.\left(x^2-y+1\right)+2019=2019\)
\(a,M-\left(3xy-4y^2\right)=x^2-7xy+8y^2\)
\(\Leftrightarrow M=x^2-7xy+8y^2+\left(3xy-4y^2\right)\)
\(\Leftrightarrow x^2-7xy+8y^2+3xy-4y^2\)
\(\Leftrightarrow x^2+\left(-7xy+3xy\right)+\left(8y^2-4y^2\right)\)
\(\Leftrightarrow x^2+\left(-4xy\right)+4y^2\)
\(\Rightarrow M=x^2+\left(-4xy\right)+4y^2\)