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. ^^

thank bn nhiều nha

1. a(b+c)+3b+3c=a(b+c)+3(b+c)=(b+c)(a+3)

2.a(m-n)+(m-n)=(m-n)(a+1)

3. 7a² -7ax-9a+9x=7a(a-x)-9(a-x)=(a-x)(7w-9

4. 4x+by+4y+bx=(4x+4y)+(by+bx)

5. ay-ax-2x+2y=(ay+2y)-(ax+2x)=y(a+2)-x(a+2)=(a+2)(y-x)

\(=7\left(a-b\right)+\left(a-b\right)\left(a+b\right)=\left(a-b\right)\left(7+a+b\right)\)

\(7a-7b+a^2-b^2\)

\(=7\left(a-b\right)+\left(a-b\right)\left(a+b\right)\)

\(=\left(a-b\right)\left(a+b+7\right)\)

=(x-5)(x-4)

\(=x^2-4x-5x+20=\left(x-4\right)\left(x-5\right)\)

\(x^2-9x+20=\left(x^2-4x\right)-\left(5x-20\right)=x\left(x-4\right)-5\left(x-4\right)=\left(x-4\right)\left(x-5\right)\)

A=\(x^2-9x\)

\(=x\cdot x-x\cdot9\)

=x(x-9)

\(3x^2-6x+9x^2=12x^2-6x=6x\left(2x-1\right)\)

\(-9x^2+6x+y^2-1\)

\(=-\left(9x^2-6x+1-y^2\right)\)

\(=-\left(3x-1-y\right)\left(3x-1+y\right)\)

\(9x^2-4\left(x-1\right)^2\)

\(=\left[3x+2\left(x-1\right)\right]\left[3x-2\left(x-1\right)\right]\)

\(=\left[3x+2x-2\right]\left[3x-2x+2\right]\)

\(=\left(5x-2\right)\left(x+2\right)\)

Trí làm đúng rồi nha

\(12y-9x^2+36-3x^2y\)

\(=\left(36-9x^2\right)-\left(3x^2y-12y\right)\)

\(=-9\left(x^2-4\right)-3y\left(x^2-4\right)\)

\(=\left(-3\right)\left(x-2\right)\left(x+2\right)\left(3+y\right)\)

\(12y-9x^2+36-3x^2y\)

\(=\left(12y-3x^2y\right)-\left(9x^2-36\right)\)

\(=3y\left(4-x^2\right)-9\left(x^2-4\right)\)

\(=3y\left(4-x^2\right)+9\left(4-x^2\right)\)

\(=\left(3y+9\right)\left(4-x^2\right)\)

\(=3\left(y+3\right)\left[\left(2^2\right)-x^2\right]\)

\(=3\left(y+3\right)\left(2+x\right)\left(2-x\right)\)

=(−3)(x−2)(x+2)(3+y)