\(1,\\ a,=\left(x+1\right)\left(x-3y\right)\\ b,=\left(a-b\right)\left(3+x\right)\\ c,=\left(x^2+3\right)\left(x+3\right)\\ d,=7x\left(x-2y\right)+2\left(x-2y\right)=\left(7x+2\right)\left(x-2y\right)\\ e,=x^2\left(a-b\right)-x\left(a-b\right)-\left(a-b\right)=\left(x^2-x-1\right)\left(a-b\right)\\ f,=16-\left(x-y\right)^2=\left(16-x+y\right)\left(16+x-y\right)\\ g,=\left(4x-5y\right)\left(4x+5y\right)+3\left(4x-5y\right)=\left(4x-5y\right)\left(4x+5y+3\right)\\ h,=\left(3x-1\right)^2-\left(x-3y\right)^2=\left(3x-1-x+3y\right)\left(3x-1+x-3y\right)=\left(2x+3y-1\right)\left(4x-3y-1\right)\\ i,=\left(x+3\right)^2\\ k,=\left(x-y\right)^2-\left(z-3t\right)^2=\left(x-y-z+3t\right)\left(x-y+z-3t\right)\\ l,=\left(x-2\right)\left(x^2+2x+4\right)+6x\left(x-2\right)=\left(x-2\right)\left(x^2+8x+4\right)\)
a. x2 - 3xy + x - 3y
= x(x - 3y) + (x - 3y)
= (x + 1)(x - 3y)
các câu còn lại tương tự
h. 9x2 - 6x + 1 - (x2 - 6xy + 9y2)
= (9x2 - 6x + 1) - (x2 - 6xy + 9y2)
= (3x - 1)2 - (x - 3y)2
= (3x - 1 - x + 3y)(3x - 1 + x - 3y)
= (2x - 1 + 3y)(4x - 1 - 3y)
