①5x^2+6xy-8y^2
=(5x-4y)(x+2y)
②x的n+2次-x^n-x^2+2x-1
=x^n(x²-1)-(x-1)²
=(x-1)(x^n+1+x^n-x+1)
③2x^3+x^2-8x-4
=x²(2x+1)-4(2x+1)
=(2x+1)(x²-4)
=(2x+1)(x+2)(x-2)
①5x^2+6xy-8y^2
=(5x-4y)(x+2y)
②x的n+2次-x^n-x^2+2x-1
=x^n(x²-1)-(x-1)²
=(x-1)(x^n+1+x^n-x+1)
③2x^3+x^2-8x-4
=x²(2x+1)-4(2x+1)
=(2x+1)(x²-4)
=(2x+1)(x+2)(x-2)