a)
\(x^3-7x-6=x^3-x-6x-6\)
\(=x(x^2-1)-6(x+1)\)
\(=x(x-1)(x+1)-6(x+1)=(x+1)[x(x-1)-6]\)
\(=(x+1)(x^2-x-6)=(x+1)[x^2-3x+2x-6]\)
\(=(x+1)[x(x-3)+2(x-3)]=(x+1)(x+2)(x-3)\)
b) \(x^3-6x^2+8x\)
\(=x(x^2-6x+8)\)
\(=x(x^2-4x-2x+8)\)
\(=x[x(x-4)-2(x-4)]=x(x-2)(x-4)\)
c) \(x^4+2x^3-16x^2-2x+15\)
\(=(x^4+2x^3-x^2-2x)-15x^2+15\)
\(=[(x^4-x^2)+(2x^3-2x)]-15(x^2-1)\)
\(=[x^2(x^2-1)+2x(x^2-1)]-15(x^2-1)\)
\(=(x^2-1)(x^2+2x)-15(x^2-1)=(x^2-1)(x^2+2x-15)\)
\(=(x^2-1)(x^2-3x+5x-15)=(x^2-1)[x(x-3)+5(x-3)]\)
\(=(x^2-1)(x+5)(x-3)=(x-1)(x+1)(x+5)(x-3)\)
d)
\(x^3-11x^2+30x=x(x^2-11x+30)\)
\(=x(x^2-5x-6x+30)\)
\(=x[x(x-5)-6(x-5)]=x(x-6)(x-5)\)
a) x3 -7x -6
=x3 -x-6x-6
= x(x2 -1)-6(x-1)
= x(x-1)(x+1)-6(x-1)
=(x-1)(x2 +x+6)
d) x3 -11x2 +30x
=x(x2 -11x+30)
= x [x2 -5x-6x +30]
=x [ x(x-5)-6(x-5)]
=x(x-6)(x-5)