Question

what are the roots of
y = x^3 - 2x^2 - 5x + 6
&
y = x^2 - x - 20

Answer 1

For the first equation, you can check that y=1 is a root of the equation. Using synthetic division, you get the polynomial x^2-x-6 as the remainder. By factoring we see that the two factors of this polynomial are, (x-3)(x+2), so the last two roots are 3 and -2.

For the second equation, it can easily be factored into (x-5)(x+4), so the roots are 5 and -4.

Answer 2

thank you! & thanks for explaining . by the way for the 2nd one there's 3 roots! so were missing one :) @clevername

Answer 3

help!

Answer 4

It's a degree 2 polynomial (the highest power of x is x^2) so there are either 0 or 2 roots (in this case 2). Unless there's an x^3 somewhere (maybe you typed it wrong?), those are the only roots. You can graph it or go to wolframalpha to check it.