Bài này lm sao dùng hằng đẳng thức đc bn,tùy câu thôi
a,\(x^2+5x-6\)
\(=x^2+6x-x-6\)
\(=x\left(x+6\right)-\left(x+6\right)\)
\(=\left(x+6\right)\left(x-1\right)\)
\(b,7x-6x^2-2\)
\(=-6x^2+7x-2\)
\(=-6x^2+3x+4x-2\)
\(=-3x\left(2x-1\right)+2\left(2x-1\right)\)
\(=\left(2x-1\right)\left(2-3x\right)\)
\(c,5x\left(x-1\right)-3x\left(x-1\right)\)
\(=x\left(x-1\right)\left(5-3\right)\)
\(=2x\left(x-1\right)\)
\(d,\left(3x+1\right)^2-\left(x+1\right)^2\)
\(=\left(3x+1-x-1\right)\left(3x+1+x+1\right)\)
\(=2x\left(4x+2\right)\)
\(=4x\left(2x+1\right)\)
\(d,x^6-y^6\)
\(=\left(x^2\right)^3-\left(y^2\right)^3\)
\(=\left(x^2-y^2\right)\left(x^4+x^2y^2+y^4\right)\)
\(=\left(x-y\right)\left(x+y\right)\left(x^4+x^2y^2+y^4\right)\)
a) x2 + 5x - 6
= x2 + 6x - x - 6
= x(x + 6) - (x + 6)
= (x + 6)(x - 1)
b) 7x - 6x2 - 2
= -6x2 + 3x + 4x - 2
= 3x(1 - 2x) - 2(1 - 2x)
= (1 - 2x)(3x - 2)
c) 5x(x - 1) - 3x(x - 1)
= (x - 1)(5x - 3x)
= 2x(x - 1)
d) (3x + 1)2 - (x + 1)2
= (3x + 1 + x + 1)(3x + 1 - x - 1)
= 2x(4x + 2)
e) x6 - y6
= (x3)2 - (y3)2
= (x3 - y3)(x3 + y3)
= (x - y)(x2 + xy + y2)(x + y)(x2 - xy + y2)
