5x(16x^3-12x^2-12x-9)
5x(2x-3)(8x^2+6x+3)
the discriminant of the quadratic is negative, so it has no real factors.
80x^4 - 60x^3 - 60x^2 - 45x
2 answers
80x^4 - 60x^3 - 60x^2 - 45x
This one looks more promising.
= 5x(16x^3 - 12x^2 - 12x - 9)
let f(x) = 16x^3 - 12x^2 - 12x - 9
f(±1) ≠ 0
f(±3) ≠ 0
tried ±3/2, ±3/4, ±3/8, ±3/16
found f(3/2) = 16(27/8) - 12(9/4) - 12(3/2) - 9
= 54 - 27 - 18 - 9 = 0
so 2x-3 is a factor
Using long division divide 16x^3 - 12x^2 - 12x - 9 by 2x-3 and you should have an exact division
let me know what you got
This one looks more promising.
= 5x(16x^3 - 12x^2 - 12x - 9)
let f(x) = 16x^3 - 12x^2 - 12x - 9
f(±1) ≠ 0
f(±3) ≠ 0
tried ±3/2, ±3/4, ±3/8, ±3/16
found f(3/2) = 16(27/8) - 12(9/4) - 12(3/2) - 9
= 54 - 27 - 18 - 9 = 0
so 2x-3 is a factor
Using long division divide 16x^3 - 12x^2 - 12x - 9 by 2x-3 and you should have an exact division
let me know what you got