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Ta có :
\(mx^2-4mx+4m-nx^2+4nx-4n\)
\(=\left(mx^2-4mx+4m\right)-\left(nx^2-4nx+4n\right)\)
\(=m\left(x^2-4x+4\right)-n\left(x^2-4x+4\right)\)
\(=m\left(x-2\right)^2-n\left(x-2\right)^2\)
\(=\left(x-2\right)^2\left(m-n\right)\)
a) \(mx^2-4mx+4m-nx^2+4nx-4n\)
\(=\left(mx^2-nx^2\right)-\left(4mx-4nx\right)+\left(4m-4n\right)\)
\(=x^2\left(m-n\right)-4x\left(m-n\right)+4\left(m-n\right)\)
\(=\left(m-n\right)\left(x^2-4x+4\right)\)
\(=\left(m-n\right)\left(x-2\right)^2\)
b) \(3x^2+48+24x-12y^2\)
\(=3\left(x^2+8x+16-4y^2\right)\)
\(=3\left[\left(x+4\right)^2-\left(2y\right)^2\right]\)
\(=3\left(x+4-2y\right)\left(x+4+2y\right)\)
a) \(mx^2-4mx+4m-nx^2+4nx-4n\)
\(=\left(mx^2-nx^2\right)-\left(4mx+4nx\right)+\left(4m-4n\right)\)
\(=x^2\left(m-n\right)-4x\left(m-n\right)+4\left(m-n\right)\)
\(=\left(m-n\right).\left(x^2-4x+4\right)\)
\(=\left(m-n\right).\left(x-2\right)^2\)
b) \(3x^2+48+24x-12y^2\)
\(=3\left(x^2+16+8x-4y^2\right)\)
\(=3\left[\left(x^2+8x+16\right)-\left(2y\right)^2\right]\)
\(=3\left[\left(x+4\right)^2-\left(2y\right)^2\right]\)
\(=3\left(x+4-2y\right).\left(x+4+2y\right)\)
1) \(5x^2-5xy-9x+9y\)
\(=5x\left(x-y\right)-9\left(x-y\right)\)
\(=\left(5x-9\right)\left(x-y\right)\)
2) \(m^3+4m^2+3m\)
\(=m^3+3m^2+m^2+3m\)
\(=m^2.\left(m+3\right)+m\left(m+3\right)\)
\(=\left(m^2+m\right)\left(m+3\right)\)
\(=m\left(m+1\right)\left(m+3\right)\)
3) \(x^2-2xy-15y^2\)
\(=x^2-2xy+y^2-16y^2\)
\(=\left(x-y\right)^2-\left(4y\right)^2\)
\(=\left(x-y-4y\right)\left(x-y+4y\right)\)
\(x^2-y^2+4x+4\)
\(=\left(x+2\right)^2-y^2\)
\(=\left(x+2+y\right)\left(x+2-y\right)\)
\(4x^2-y^2+8\left(y-2\right)\)
\(=4x^2-\left(y^2-8y+16\right)\)
\(=4x^2-\left(y-4\right)^2\)
\(=\left(2x+y-4\right)\left(2x-y+4\right)\)
Bổ sung nha :
(x - y)2 - (2m - n)2
= (x - y -2m - n) . (x - y + 2m - n) .
Chúc bạn học tốt !
x2-2xy+y2-4m2+4mn-n2 mới đúng tui giải cho
<=> (x-y)2-(4m-n)2< Áp dụng hằng đẳng thức số 2 >
<=> (x-y-4m-2).(x-y+4m-2) < HĐT số 3 >
Đề sai nhé .Sửu lại
\(x^2-4x^2y^2+4+4x\)
\(=\left(x^2+4x+4\right)-4x^2y^2\)
\(=\left(x+2\right)^2-\left(2xy\right)^2\)
\(=\left(x+2+2xy\right)\left(x+2-2xy\right)\)
\(x^8+3x^4+4\)
\(=\left(x^8-x^6+2x^4\right)+\left(x^6-x^4+2x^2\right)+\left(2x^4-2x^2+4\right)\)
\(=x^4\left(x^4-x^2+2\right)+x^2\left(x^4-x^2+2\right)+2\left(x^4-x^2+2\right)\)
\(=\left(x^4+x^2+2\right)\left(x^4-x^2+2\right)\)
\(4x^4+4x^3+5x^2+2x+1\)
\(=\left(4x^4+2x^3+2x^2\right)+\left(2x^3+x^2+x\right)+\left(2x^2+x+1\right)\)
\(=2x^2\left(2x^2+x+1\right)+x\left(2x^2+x+1\right)+\left(2x^2+x+1\right)\)
\(=\left(2x^2+x+1\right)^2\)
\(mx^2-4mx+4m-nx^2+4nx-4n\)
\(=\left(mx^2-4mx+4m\right)-\left(nx^2-4nx+4n\right)\)
\(=m\left(x^2-4x+4\right)-n\left(x^2-4x+4\right)\)
\(=\left(m-n\right)\left(x^2-4x+4\right)\)
\(=\left(m-n\right)\left(x-2\right)^2\)
\(mx^2-4mx+4m-nx^2+4nx-4n\)
\(=x^2\left(m-n\right)+4x\left(n-m\right)+4\left(m-n\right)\)
\(=x^2\left(m-n\right)-4x\left(m-n\right)+4\left(m-n\right)\)
\(=\left(x^2-4x+4\right)\left(m-n\right)\)
\(=\left(x-2\right)^2\left(m-n\right)\)