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Bài 2 : Phân tích các đa thức sau thành nhân tử :
a) x2 - ( m + n )x + mn
b) ax + by + a - bx - ay - b
\(a,=x^2-mx-nx+mn=x\left(x-m\right)-n\left(x-m\right)=\left(x-n\right)\left(x-m\right)\\ b,=a\left(x-y\right)-b\left(x-y\right)+\left(a-b\right)\\ =\left(x-y\right)\left(a-b\right)+\left(a-b\right)=\left(a-b\right)\left(x-y+1\right)\)
b: \(=a\left(x-y\right)-b\left(x-y\right)+a-b\)
\(=\left(x-y+1\right)\left(a-b\right)\)
Bài 4:
Ta có: \(\left(x^3-x^2\right)-4x^2+8x-4=0\)
\(\Leftrightarrow x^2\left(x-1\right)-4\left(x-1\right)^2=0\)
\(\Leftrightarrow\left(x-1\right)\left(x-2\right)^2=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=1\\x=2\end{matrix}\right.\)
a, (4x+4y)+(by+bx)= 4(x+y)+b(x+y)=(x+y)(4+b)
b, ( 2x2+xy)-(2x+y)= x(2x+y)-(2x+y)=(2x+y)(x-1)
c, (3ax-2bx)-(6ay-4by)= x(3a-2b)-2y(3a-2b)=(3a-2b)(x-2y)
d, (ma+na-pa)-(mb+nb-pb)= a(m+n+p)-b(m+n-p)=(m+n+p)(a-b)
a) 4x+bx+by+4y b)2x2+xy-2x-y c)3ax-2bx-6ay+4by d)ma-mb+na-nb-pa+pb
=x(4+b)+y(b+4) =2x(x-1)+y(x-1) =3ax-6ay-2bx+4by =m(a-b)+n(a-b)-p(a-b)
=(x+y)(b+4) =(x-1)(2x+1) =3a(x-2y)-2b(x-2y)=(3a-2b)(x-2y) =(a-b)(m+n-p)
1, \(a.\left(b+c\right)+3b+3c=a.\left(b+c\right)+3.\left(b+c\right)\)= \(\left(b+c\right).\left(3+a\right)\)
2, \(a.\left(m-n\right)+\left(m-n\right)=\left(m-n\right).\left(a+1\right)\)
3, \(7a^2-7ax-9a+9x=7a.\left(a-x\right)-9.\left(a-x\right)\)= \(\left(a-x\right).\left(7a-9\right)\)
4, \(4x+by+4y+bx=4.\left(x+y\right)+b.\left(x+y\right)\)= \(\left(x+y\right).\left(4+b\right)\)
5, \(ay-ax-2x+2y=a.\left(y-x\right)+2.\left(y-x\right)\)= \(\left(y-x\right).\left(a+2\right)\)
Chúc bạn học tốt. Có gì không hiểu thì chat hỏi mik nhé. ^^
\(a,\left(2a+3\right)x-\left(2a+3\right)y+\left(2a+3\right)\)
\(=\left(2a+3\right)\left(x-y+1\right)\)
\(b,\left(4x-y\right)\left(a-1\right)-\left(y-4x\right)\left(b-1\right)+\left(4x-y\right)\left(1-c\right)\)
\(=\left(4x-y\right)\left(a-1\right)+\left(4x-y\right)\left(b-1\right)+\left(4x-y\right)\left(1-c\right)\)
\(=\left(4x-y\right)\left(a-1+b-1+1-c\right)\)
\(=\left(4x-y\right)\left(a+b-c-1\right)\)
\(c,x^k+1-x^k-1\)
\(=0?!?!\)
\(d,x^m+3-x^m+1\)
\(=4\)
\(e,3\left(x-y\right)^3-2\left(x-y\right)^2\)
\(=\left(x-y\right)^2\left(3\left(x-y\right)-2\right)\)
\(=\left(x-y\right)^2\left(3x-3y-2\right)\)
\(f,81a^2+18a+1\)
\(=\left(9a\right)^2+2.9a+1\)
\(=\left(9a+1\right)^2\)
\(g,25a^2.b^2-16c^2\)
\(=\left(5ab\right)^2-\left(4c\right)^2\)
\(=\left(5ab+4c\right)\left(5ab-4c\right)\)
\(h,\left(a-b\right)^2-2\left(a-b\right)c+c^2\)
\(=\left(a-b-c\right)^2\)
\(i,\left(ax+by\right)^2-\left(ax-by\right)^2\)
\(=\left(ax+by-ax+by\right)\left(ax+by+ax-by\right)\)
\(=2by.2ax\)
\(=4axby\)
Bài 1:
a) \(7x^2\left(x^2-5x+1\right)=7x^4-35x^3+7x^2\)
b) \(\left(2x-3\right)\left(x+7\right)=2x^2+11x-21\)
Bài 2:
a) \(4x^2y-8x^3y^2=4x^2y\left(1-2xy\right)\)
b) \(2x-4y-ax+2ay=x\left(2-a\right)-2y\left(2-a\right)=\left(2-a\right)\left(x-2y\right)\)
\(a.a\left(m-n\right)+m-n\)
\(=a\left(m-n\right)+\left(m-n\right)\)
\(=\left(a+1\right)\left(m-n\right)\)
\(b.ma+mb-a-b\)
\(=m\left(a+b\right)-\left(a+b\right)\)
\(=\left(m-1\right)\left(a+b\right)\)
\(c.4x+by+4y+bx\)
\(=\left(4x+4y\right)+\left(bx+by\right)\)
\(=4\left(x+y\right)+b\left(x+y\right)\)
\(=\left(b+4\right)\left(x+y\right)\)
\(d.1-ax-x+a\)
\(=\left(a-ax\right)+\left(1-x\right)\)
\(=a\left(1-x\right)+\left(1-x\right)\)
\(=\left(a+1\right)\left(1-x\right)\)
1.a(m-n)+m-n=am-an+m-n=(am+m)-(an+n)=m(a+1)-n(a+1)=(a+1)(m-n)
2.ma+mb-a-b=(ma-a)+(mb-b)=a(m-1)+b(m-1)=(m-1)(a+b)
3.4x+by+4y+bx=(4x+bx)+(4y+by)=x(4+b)+y(4+b)=(4+b)(x+y)
4.1-ax-x+a=(1+a)-(ax+x)=(1+a)-x(a+1)=(1+a)(1-x)